from sympy.core.function import (Derivative, Function, diff)
from sympy.core.mul import Mul
from sympy.core.numbers import (I, Rational, pi)
from sympy.core.relational import Eq
from sympy.core.singleton import S
from sympy.core.symbol import (Symbol, symbols)
from sympy.functions.elementary.hyperbolic import sinh
from sympy.functions.elementary.miscellaneous import sqrt
from sympy.matrices.dense import Matrix
from sympy.core.containers import Tuple
from sympy.functions import exp, cos, sin, log, Ci, Si, erf, erfi
from sympy.matrices import dotprodsimp, NonSquareMatrixError
from sympy.solvers.ode import dsolve
from sympy.solvers.ode.ode import constant_renumber
from sympy.solvers.ode.subscheck import checksysodesol
from sympy.solvers.ode.systems import (_classify_linear_system, linear_ode_to_matrix,
                                       ODEOrderError, ODENonlinearError, _simpsol,
                                       _is_commutative_anti_derivative, linodesolve,
                                       canonical_odes, dsolve_system, _component_division,
                                       _eqs2dict, _dict2graph)
from sympy.functions import airyai, airybi
from sympy.integrals.integrals import Integral
from sympy.simplify.ratsimp import ratsimp
from sympy.testing.pytest import raises, slow, tooslow, XFAIL


C0, C1, C2, C3, C4, C5, C6, C7, C8, C9, C10 = symbols('C0:11')
x = symbols('x')
f = Function('f')
g = Function('g')
h = Function('h')


def test_linear_ode_to_matrix():
    f, g, h = symbols("f, g, h", cls=Function)
    t = Symbol("t")
    funcs = [f(t), g(t), h(t)]
    f1 = f(t).diff(t)
    g1 = g(t).diff(t)
    h1 = h(t).diff(t)
    f2 = f(t).diff(t, 2)
    g2 = g(t).diff(t, 2)
    h2 = h(t).diff(t, 2)

    eqs_1 = [Eq(f1, g(t)), Eq(g1, f(t))]
    sol_1 = ([Matrix([[1, 0], [0, 1]]), Matrix([[ 0, 1], [1,  0]])], Matrix([[0],[0]]))
    assert linear_ode_to_matrix(eqs_1, funcs[:-1], t, 1) == sol_1

    eqs_2 = [Eq(f1, f(t) + 2*g(t)), Eq(g1, h(t)), Eq(h1, g(t) + h(t) + f(t))]
    sol_2 = ([Matrix([[1, 0, 0], [0, 1, 0], [0, 0, 1]]), Matrix([[1, 2,  0], [ 0,  0, 1], [1, 1, 1]])],
             Matrix([[0], [0], [0]]))
    assert linear_ode_to_matrix(eqs_2, funcs, t, 1) == sol_2

    eqs_3 = [Eq(2*f1 + 3*h1, f(t) + g(t)), Eq(4*h1 + 5*g1, f(t) + h(t)), Eq(5*f1 + 4*g1, g(t) + h(t))]
    sol_3 = ([Matrix([[2, 0, 3], [0, 5, 4], [5, 4, 0]]), Matrix([[1, 1,  0], [1,  0, 1], [0, 1, 1]])],
             Matrix([[0], [0], [0]]))
    assert linear_ode_to_matrix(eqs_3, funcs, t, 1) == sol_3

    eqs_4 = [Eq(f2 + h(t), f1 + g(t)), Eq(2*h2 + g2 + g1 + g(t), 0), Eq(3*h1, 4)]
    sol_4 = ([Matrix([[1, 0, 0], [0, 1, 2], [0, 0, 0]]), Matrix([[1, 0, 0], [0, -1, 0], [0, 0, -3]]),
              Matrix([[0, 1, -1], [0,  -1, 0], [0, 0, 0]])], Matrix([[0], [0], [4]]))
    assert linear_ode_to_matrix(eqs_4, funcs, t, 2) == sol_4

    eqs_5 = [Eq(f2, g(t)), Eq(f1 + g1, f(t))]
    raises(ODEOrderError, lambda: linear_ode_to_matrix(eqs_5, funcs[:-1], t, 1))

    eqs_6 = [Eq(f1, f(t)**2), Eq(g1, f(t) + g(t))]
    raises(ODENonlinearError, lambda: linear_ode_to_matrix(eqs_6, funcs[:-1], t, 1))


def test__classify_linear_system():
    x, y, z, w = symbols('x, y, z, w', cls=Function)
    t, k, l = symbols('t k l')
    x1 = diff(x(t), t)
    y1 = diff(y(t), t)
    z1 = diff(z(t), t)
    w1 = diff(w(t), t)
    x2 = diff(x(t), t, t)
    y2 = diff(y(t), t, t)
    funcs = [x(t), y(t)]
    funcs_2 = funcs + [z(t), w(t)]

    eqs_1 = (5 * x1 + 12 * x(t) - 6 * (y(t)), (2 * y1 - 11 * t * x(t) + 3 * y(t) + t))
    assert _classify_linear_system(eqs_1, funcs, t) is None

    eqs_2 = (5 * (x1**2) + 12 * x(t) - 6 * (y(t)), (2 * y1 - 11 * t * x(t) + 3 * y(t) + t))
    sol2 = {'is_implicit': True,
            'canon_eqs': [[Eq(Derivative(x(t), t), -sqrt(-12*x(t)/5 + 6*y(t)/5)),
            Eq(Derivative(y(t), t), 11*t*x(t)/2 - t/2 - 3*y(t)/2)],
            [Eq(Derivative(x(t), t), sqrt(-12*x(t)/5 + 6*y(t)/5)),
            Eq(Derivative(y(t), t), 11*t*x(t)/2 - t/2 - 3*y(t)/2)]]}
    assert _classify_linear_system(eqs_2, funcs, t) == sol2

    eqs_2_1 = [Eq(Derivative(x(t), t), -sqrt(-12*x(t)/5 + 6*y(t)/5)),
            Eq(Derivative(y(t), t), 11*t*x(t)/2 - t/2 - 3*y(t)/2)]
    assert _classify_linear_system(eqs_2_1, funcs, t) is None

    eqs_2_2 = [Eq(Derivative(x(t), t), sqrt(-12*x(t)/5 + 6*y(t)/5)),
            Eq(Derivative(y(t), t), 11*t*x(t)/2 - t/2 - 3*y(t)/2)]
    assert _classify_linear_system(eqs_2_2, funcs, t) is None

    eqs_3 = (5 * x1 + 12 * x(t) - 6 * (y(t)), (2 * y1 - 11 * x(t) + 3 * y(t)), (5 * w1 + z(t)), (z1 + w(t)))
    answer_3 = {'no_of_equation': 4,
     'eq': (12*x(t) - 6*y(t) + 5*Derivative(x(t), t),
      -11*x(t) + 3*y(t) + 2*Derivative(y(t), t),
      z(t) + 5*Derivative(w(t), t),
      w(t) + Derivative(z(t), t)),
     'func': [x(t), y(t), z(t), w(t)],
     'order': {x(t): 1, y(t): 1, z(t): 1, w(t): 1},
     'is_linear': True,
     'is_constant': True,
     'is_homogeneous': True,
     'func_coeff': -Matrix([
     [Rational(12, 5), Rational(-6, 5), 0, 0],
     [Rational(-11, 2),  Rational(3, 2),   0, 0],
     [0, 0, 0, 1],
     [0, 0, Rational(1, 5), 0]]),
     'type_of_equation': 'type1',
     'is_general': True}
    assert _classify_linear_system(eqs_3, funcs_2, t) == answer_3

    eqs_4 = (5 * x1 + 12 * x(t) - 6 * (y(t)), (2 * y1 - 11 * x(t) + 3 * y(t)), (z1 - w(t)), (w1 - z(t)))
    answer_4 = {'no_of_equation': 4,
     'eq': (12 * x(t) - 6 * y(t) + 5 * Derivative(x(t), t),
            -11 * x(t) + 3 * y(t) + 2 * Derivative(y(t), t),
            -w(t) + Derivative(z(t), t),
            -z(t) + Derivative(w(t), t)),
     'func': [x(t), y(t), z(t), w(t)],
     'order': {x(t): 1, y(t): 1, z(t): 1, w(t): 1},
     'is_linear': True,
     'is_constant': True,
     'is_homogeneous': True,
     'func_coeff': -Matrix([
         [Rational(12, 5), Rational(-6, 5), 0, 0],
         [Rational(-11, 2), Rational(3, 2), 0, 0],
         [0, 0, 0, -1],
         [0, 0, -1, 0]]),
     'type_of_equation': 'type1',
     'is_general': True}
    assert _classify_linear_system(eqs_4, funcs_2, t) == answer_4

    eqs_5 = (5*x1 + 12*x(t) - 6*(y(t)) + x2, (2*y1 - 11*x(t) + 3*y(t)), (z1 - w(t)), (w1 - z(t)))
    answer_5 = {'no_of_equation': 4, 'eq': (12*x(t) - 6*y(t) + 5*Derivative(x(t), t) + Derivative(x(t), (t, 2)),
                -11*x(t) + 3*y(t) + 2*Derivative(y(t), t), -w(t) + Derivative(z(t), t), -z(t) + Derivative(w(t),
                t)), 'func': [x(t), y(t), z(t), w(t)], 'order': {x(t): 2, y(t): 1, z(t): 1, w(t): 1}, 'is_linear':
                True, 'is_homogeneous': True, 'is_general': True, 'type_of_equation': 'type0', 'is_higher_order': True}
    assert _classify_linear_system(eqs_5, funcs_2, t) == answer_5

    eqs_6 = (Eq(x1, 3*y(t) - 11*z(t)), Eq(y1, 7*z(t) - 3*x(t)), Eq(z1, 11*x(t) - 7*y(t)))
    answer_6 = {'no_of_equation': 3, 'eq': (Eq(Derivative(x(t), t), 3*y(t) - 11*z(t)), Eq(Derivative(y(t), t), -3*x(t) + 7*z(t)),
            Eq(Derivative(z(t), t), 11*x(t) - 7*y(t))), 'func': [x(t), y(t), z(t)], 'order': {x(t): 1, y(t): 1, z(t): 1},
            'is_linear': True, 'is_constant': True, 'is_homogeneous': True,
            'func_coeff': -Matrix([
                         [  0, -3, 11],
                         [  3,  0, -7],
                         [-11,  7,  0]]),
            'type_of_equation': 'type1', 'is_general': True}

    assert _classify_linear_system(eqs_6, funcs_2[:-1], t) == answer_6

    eqs_7 = (Eq(x1, y(t)), Eq(y1, x(t)))
    answer_7 = {'no_of_equation': 2, 'eq': (Eq(Derivative(x(t), t), y(t)), Eq(Derivative(y(t), t), x(t))),
                'func': [x(t), y(t)], 'order': {x(t): 1, y(t): 1}, 'is_linear': True, 'is_constant': True,
                'is_homogeneous': True, 'func_coeff': -Matrix([
                                                        [ 0, -1],
                                                        [-1,  0]]),
                'type_of_equation': 'type1', 'is_general': True}
    assert _classify_linear_system(eqs_7, funcs, t) == answer_7

    eqs_8 = (Eq(x1, 21*x(t)), Eq(y1, 17*x(t) + 3*y(t)), Eq(z1, 5*x(t) + 7*y(t) + 9*z(t)))
    answer_8 = {'no_of_equation': 3, 'eq': (Eq(Derivative(x(t), t), 21*x(t)), Eq(Derivative(y(t), t), 17*x(t) + 3*y(t)),
            Eq(Derivative(z(t), t), 5*x(t) + 7*y(t) + 9*z(t))), 'func': [x(t), y(t), z(t)], 'order': {x(t): 1, y(t): 1, z(t): 1},
            'is_linear': True, 'is_constant': True, 'is_homogeneous': True,
            'func_coeff': -Matrix([
                            [-21,  0,  0],
                            [-17, -3,  0],
                            [ -5, -7, -9]]),
            'type_of_equation': 'type1', 'is_general': True}

    assert _classify_linear_system(eqs_8, funcs_2[:-1], t) == answer_8

    eqs_9 = (Eq(x1, 4*x(t) + 5*y(t) + 2*z(t)), Eq(y1, x(t) + 13*y(t) + 9*z(t)), Eq(z1, 32*x(t) + 41*y(t) + 11*z(t)))
    answer_9 = {'no_of_equation': 3, 'eq': (Eq(Derivative(x(t), t), 4*x(t) + 5*y(t) + 2*z(t)),
                Eq(Derivative(y(t), t), x(t) + 13*y(t) + 9*z(t)), Eq(Derivative(z(t), t), 32*x(t) + 41*y(t) + 11*z(t))),
                'func': [x(t), y(t), z(t)], 'order': {x(t): 1, y(t): 1, z(t): 1}, 'is_linear': True,
                'is_constant': True, 'is_homogeneous': True,
                'func_coeff': -Matrix([
                            [ -4,  -5,  -2],
                            [ -1, -13,  -9],
                            [-32, -41, -11]]),
                'type_of_equation': 'type1', 'is_general': True}
    assert _classify_linear_system(eqs_9, funcs_2[:-1], t) == answer_9

    eqs_10 = (Eq(3*x1, 4*5*(y(t) - z(t))), Eq(4*y1, 3*5*(z(t) - x(t))), Eq(5*z1, 3*4*(x(t) - y(t))))
    answer_10 = {'no_of_equation': 3, 'eq': (Eq(3*Derivative(x(t), t), 20*y(t) - 20*z(t)),
                Eq(4*Derivative(y(t), t), -15*x(t) + 15*z(t)), Eq(5*Derivative(z(t), t), 12*x(t) - 12*y(t))),
                'func': [x(t), y(t), z(t)], 'order': {x(t): 1, y(t): 1, z(t): 1}, 'is_linear': True,
                'is_constant': True, 'is_homogeneous': True,
                'func_coeff': -Matrix([
                                [  0, Rational(-20, 3),  Rational(20, 3)],
                                [Rational(15, 4),     0, Rational(-15, 4)],
                                [Rational(-12, 5), Rational(12, 5),  0]]),
                'type_of_equation': 'type1', 'is_general': True}
    assert _classify_linear_system(eqs_10, funcs_2[:-1], t) == answer_10

    eq11 = (Eq(x1, 3*y(t) - 11*z(t)), Eq(y1, 7*z(t) - 3*x(t)), Eq(z1, 11*x(t) - 7*y(t)))
    sol11 = {'no_of_equation': 3, 'eq': (Eq(Derivative(x(t), t), 3*y(t) - 11*z(t)), Eq(Derivative(y(t), t), -3*x(t) + 7*z(t)),
            Eq(Derivative(z(t), t), 11*x(t) - 7*y(t))), 'func': [x(t), y(t), z(t)], 'order': {x(t): 1, y(t): 1, z(t): 1},
            'is_linear': True, 'is_constant': True, 'is_homogeneous': True, 'func_coeff': -Matrix([
            [  0, -3, 11], [  3,  0, -7], [-11,  7,  0]]), 'type_of_equation': 'type1', 'is_general': True}
    assert _classify_linear_system(eq11, funcs_2[:-1], t) == sol11

    eq12 = (Eq(Derivative(x(t), t), y(t)), Eq(Derivative(y(t), t), x(t)))
    sol12 = {'no_of_equation': 2, 'eq': (Eq(Derivative(x(t), t), y(t)), Eq(Derivative(y(t), t), x(t))),
             'func': [x(t), y(t)], 'order': {x(t): 1, y(t): 1}, 'is_linear': True, 'is_constant': True,
             'is_homogeneous': True, 'func_coeff': -Matrix([
            [0, -1],
            [-1, 0]]), 'type_of_equation': 'type1', 'is_general': True}
    assert _classify_linear_system(eq12, [x(t), y(t)], t) == sol12

    eq13 = (Eq(Derivative(x(t), t), 21*x(t)), Eq(Derivative(y(t), t), 17*x(t) + 3*y(t)),
            Eq(Derivative(z(t), t), 5*x(t) + 7*y(t) + 9*z(t)))
    sol13 = {'no_of_equation': 3, 'eq': (
    Eq(Derivative(x(t), t), 21 * x(t)), Eq(Derivative(y(t), t), 17 * x(t) + 3 * y(t)),
    Eq(Derivative(z(t), t), 5 * x(t) + 7 * y(t) + 9 * z(t))), 'func': [x(t), y(t), z(t)],
             'order': {x(t): 1, y(t): 1, z(t): 1}, 'is_linear': True, 'is_constant': True, 'is_homogeneous': True,
             'func_coeff': -Matrix([
                 [-21, 0, 0],
                 [-17, -3, 0],
                 [-5, -7, -9]]), 'type_of_equation': 'type1', 'is_general': True}
    assert _classify_linear_system(eq13, [x(t), y(t), z(t)], t) == sol13

    eq14 = (
        Eq(Derivative(x(t), t), 4*x(t) + 5*y(t) + 2*z(t)), Eq(Derivative(y(t), t), x(t) + 13*y(t) + 9*z(t)),
        Eq(Derivative(z(t), t), 32*x(t) + 41*y(t) + 11*z(t)))
    sol14 = {'no_of_equation': 3, 'eq': (
    Eq(Derivative(x(t), t), 4 * x(t) + 5 * y(t) + 2 * z(t)), Eq(Derivative(y(t), t), x(t) + 13 * y(t) + 9 * z(t)),
    Eq(Derivative(z(t), t), 32 * x(t) + 41 * y(t) + 11 * z(t))), 'func': [x(t), y(t), z(t)],
             'order': {x(t): 1, y(t): 1, z(t): 1}, 'is_linear': True, 'is_constant': True, 'is_homogeneous': True,
             'func_coeff': -Matrix([
                 [-4, -5, -2],
                 [-1, -13, -9],
                 [-32, -41, -11]]), 'type_of_equation': 'type1', 'is_general': True}
    assert _classify_linear_system(eq14, [x(t), y(t), z(t)], t) == sol14

    eq15 = (Eq(3*Derivative(x(t), t), 20*y(t) - 20*z(t)), Eq(4*Derivative(y(t), t), -15*x(t) + 15*z(t)),
            Eq(5*Derivative(z(t), t), 12*x(t) - 12*y(t)))
    sol15 = {'no_of_equation': 3, 'eq': (
    Eq(3 * Derivative(x(t), t), 20 * y(t) - 20 * z(t)), Eq(4 * Derivative(y(t), t), -15 * x(t) + 15 * z(t)),
    Eq(5 * Derivative(z(t), t), 12 * x(t) - 12 * y(t))), 'func': [x(t), y(t), z(t)],
             'order': {x(t): 1, y(t): 1, z(t): 1}, 'is_linear': True, 'is_constant': True, 'is_homogeneous': True,
             'func_coeff': -Matrix([
                 [0, Rational(-20, 3), Rational(20, 3)],
                 [Rational(15, 4), 0, Rational(-15, 4)],
                 [Rational(-12, 5), Rational(12, 5), 0]]), 'type_of_equation': 'type1', 'is_general': True}
    assert _classify_linear_system(eq15, [x(t), y(t), z(t)], t) == sol15

    # Constant coefficient homogeneous ODEs
    eq1 = (Eq(diff(x(t), t), x(t) + y(t) + 9), Eq(diff(y(t), t), 2*x(t) + 5*y(t) + 23))
    sol1 = {'no_of_equation': 2, 'eq': (Eq(Derivative(x(t), t), x(t) + y(t) + 9),
        Eq(Derivative(y(t), t), 2*x(t) + 5*y(t) + 23)), 'func': [x(t), y(t)],
        'order': {x(t): 1, y(t): 1}, 'is_linear': True, 'is_constant': True, 'is_homogeneous': False, 'is_general': True,
        'func_coeff': -Matrix([[-1, -1], [-2, -5]]), 'rhs': Matrix([[ 9], [23]]), 'type_of_equation': 'type2'}
    assert _classify_linear_system(eq1, funcs, t) == sol1

    # Non constant coefficient homogeneous ODEs
    eq1 = (Eq(diff(x(t), t), 5*t*x(t) + 2*y(t)), Eq(diff(y(t), t), 2*x(t) + 5*t*y(t)))
    sol1 = {'no_of_equation': 2, 'eq': (Eq(Derivative(x(t), t), 5*t*x(t) + 2*y(t)), Eq(Derivative(y(t), t), 5*t*y(t) + 2*x(t))),
            'func': [x(t), y(t)], 'order': {x(t): 1, y(t): 1}, 'is_linear': True, 'is_constant': False,
            'is_homogeneous': True, 'func_coeff': -Matrix([ [-5*t,   -2], [  -2, -5*t]]), 'commutative_antiderivative': Matrix([
            [5*t**2/2,      2*t], [     2*t, 5*t**2/2]]), 'type_of_equation': 'type3', 'is_general': True}
    assert _classify_linear_system(eq1, funcs, t) == sol1

    # Non constant coefficient non-homogeneous ODEs
    eq1 = [Eq(x1, x(t) + t*y(t) + t), Eq(y1, t*x(t) + y(t))]
    sol1 = {'no_of_equation': 2, 'eq': [Eq(Derivative(x(t), t), t*y(t) + t + x(t)), Eq(Derivative(y(t), t),
            t*x(t) + y(t))], 'func': [x(t), y(t)], 'order': {x(t): 1, y(t): 1}, 'is_linear': True,
            'is_constant': False, 'is_homogeneous': False, 'is_general': True, 'func_coeff': -Matrix([ [-1, -t],
            [-t, -1]]), 'commutative_antiderivative': Matrix([ [     t, t**2/2], [t**2/2,      t]]), 'rhs':
            Matrix([ [t], [0]]), 'type_of_equation': 'type4'}
    assert _classify_linear_system(eq1, funcs, t) == sol1

    eq2 = [Eq(x1, t*x(t) + t*y(t) + t), Eq(y1, t*x(t) + t*y(t) + cos(t))]
    sol2 = {'no_of_equation': 2, 'eq': [Eq(Derivative(x(t), t), t*x(t) + t*y(t) + t), Eq(Derivative(y(t), t),
            t*x(t) + t*y(t) + cos(t))], 'func': [x(t), y(t)], 'order': {x(t): 1, y(t): 1}, 'is_linear': True,
            'is_homogeneous': False, 'is_general': True, 'rhs': Matrix([ [     t], [cos(t)]]), 'func_coeff':
            Matrix([ [t, t], [t, t]]), 'is_constant': False, 'type_of_equation': 'type4',
            'commutative_antiderivative': Matrix([ [t**2/2, t**2/2], [t**2/2, t**2/2]])}
    assert _classify_linear_system(eq2, funcs, t) == sol2

    eq3 = [Eq(x1, t*(x(t) + y(t) + z(t) + 1)), Eq(y1, t*(x(t) + y(t) + z(t))), Eq(z1, t*(x(t) + y(t) + z(t)))]
    sol3 = {'no_of_equation': 3, 'eq': [Eq(Derivative(x(t), t), t*(x(t) + y(t) + z(t) + 1)),
            Eq(Derivative(y(t), t), t*(x(t) + y(t) + z(t))), Eq(Derivative(z(t), t), t*(x(t) + y(t) + z(t)))],
            'func': [x(t), y(t), z(t)], 'order': {x(t): 1, y(t): 1, z(t): 1}, 'is_linear': True, 'is_constant':
            False, 'is_homogeneous': False, 'is_general': True, 'func_coeff': -Matrix([ [-t, -t, -t], [-t, -t,
            -t], [-t, -t, -t]]), 'commutative_antiderivative': Matrix([ [t**2/2, t**2/2, t**2/2], [t**2/2,
            t**2/2, t**2/2], [t**2/2, t**2/2, t**2/2]]), 'rhs': Matrix([ [t], [0], [0]]), 'type_of_equation':
            'type4'}
    assert _classify_linear_system(eq3, funcs_2[:-1], t) == sol3

    eq4 = [Eq(x1, x(t) + y(t) + t*z(t) + 1), Eq(y1, x(t) + t*y(t) + z(t) + 10), Eq(z1, t*x(t) + y(t) + z(t) + t)]
    sol4 = {'no_of_equation': 3, 'eq': [Eq(Derivative(x(t), t), t*z(t) + x(t) + y(t) + 1), Eq(Derivative(y(t),
            t), t*y(t) + x(t) + z(t) + 10), Eq(Derivative(z(t), t), t*x(t) + t + y(t) + z(t))], 'func': [x(t),
            y(t), z(t)], 'order': {x(t): 1, y(t): 1, z(t): 1}, 'is_linear': True, 'is_constant': False,
            'is_homogeneous': False, 'is_general': True, 'func_coeff': -Matrix([ [-1, -1, -t], [-1, -t, -1], [-t,
            -1, -1]]), 'commutative_antiderivative': Matrix([ [     t,      t, t**2/2], [     t, t**2/2,
            t], [t**2/2,      t,      t]]), 'rhs': Matrix([ [ 1], [10], [ t]]), 'type_of_equation': 'type4'}
    assert _classify_linear_system(eq4, funcs_2[:-1], t) == sol4

    sum_terms = t*(x(t) + y(t) + z(t) + w(t))
    eq5 = [Eq(x1, sum_terms), Eq(y1, sum_terms), Eq(z1, sum_terms + 1), Eq(w1, sum_terms)]
    sol5 = {'no_of_equation': 4, 'eq': [Eq(Derivative(x(t), t), t*(w(t) + x(t) + y(t) + z(t))),
            Eq(Derivative(y(t), t), t*(w(t) + x(t) + y(t) + z(t))), Eq(Derivative(z(t), t), t*(w(t) + x(t) +
            y(t) + z(t)) + 1), Eq(Derivative(w(t), t), t*(w(t) + x(t) + y(t) + z(t)))], 'func': [x(t), y(t),
            z(t), w(t)], 'order': {x(t): 1, y(t): 1, z(t): 1, w(t): 1}, 'is_linear': True, 'is_constant': False,
            'is_homogeneous': False, 'is_general': True, 'func_coeff': -Matrix([ [-t, -t, -t, -t], [-t, -t, -t,
            -t], [-t, -t, -t, -t], [-t, -t, -t, -t]]), 'commutative_antiderivative': Matrix([ [t**2/2, t**2/2,
            t**2/2, t**2/2], [t**2/2, t**2/2, t**2/2, t**2/2], [t**2/2, t**2/2, t**2/2, t**2/2], [t**2/2,
            t**2/2, t**2/2, t**2/2]]), 'rhs': Matrix([ [0], [0], [1], [0]]), 'type_of_equation': 'type4'}
    assert _classify_linear_system(eq5, funcs_2, t) == sol5

    # Second Order
    t_ = symbols("t_")

    eq1 = (Eq(9*x(t) + 7*y(t) + 4*Derivative(x(t), t) + Derivative(x(t), (t, 2)) + 3*Derivative(y(t), t), 11*exp(I*t)),
           Eq(3*x(t) + 12*y(t) + 5*Derivative(x(t), t) + 8*Derivative(y(t), t) + Derivative(y(t), (t, 2)), 2*exp(I*t)))
    sol1 = {'no_of_equation': 2, 'eq': (Eq(9*x(t) + 7*y(t) + 4*Derivative(x(t), t) + Derivative(x(t), (t, 2)) +
            3*Derivative(y(t), t), 11*exp(I*t)), Eq(3*x(t) + 12*y(t) + 5*Derivative(x(t), t) +
            8*Derivative(y(t), t) + Derivative(y(t), (t, 2)), 2*exp(I*t))), 'func': [x(t), y(t)], 'order':
            {x(t): 2, y(t): 2}, 'is_linear': True, 'is_homogeneous': False, 'is_general': True, 'rhs': Matrix([
            [11*exp(I*t)], [ 2*exp(I*t)]]), 'type_of_equation': 'type0', 'is_second_order': True,
            'is_higher_order': True}
    assert _classify_linear_system(eq1, funcs, t) == sol1

    eq2 = (Eq((4*t**2 + 7*t + 1)**2*Derivative(x(t), (t, 2)), 5*x(t) + 35*y(t)),
           Eq((4*t**2 + 7*t + 1)**2*Derivative(y(t), (t, 2)), x(t) + 9*y(t)))
    sol2 = {'no_of_equation': 2, 'eq': (Eq((4*t**2 + 7*t + 1)**2*Derivative(x(t), (t, 2)), 5*x(t) + 35*y(t)),
            Eq((4*t**2 + 7*t + 1)**2*Derivative(y(t), (t, 2)), x(t) + 9*y(t))), 'func': [x(t), y(t)], 'order':
            {x(t): 2, y(t): 2}, 'is_linear': True, 'is_homogeneous': True, 'is_general': True,
            'type_of_equation': 'type2', 'A0': Matrix([ [Rational(53, 4),   35], [   1, Rational(69, 4)]]), 'g(t)': sqrt(4*t**2 + 7*t
            + 1), 'tau': sqrt(33)*log(t - sqrt(33)/8 + Rational(7, 8))/33 - sqrt(33)*log(t + sqrt(33)/8 + Rational(7, 8))/33,
            'is_transformed': True, 't_': t_, 'is_second_order': True, 'is_higher_order': True}
    assert _classify_linear_system(eq2, funcs, t) == sol2

    eq3 = ((t*Derivative(x(t), t) - x(t))*log(t) + (t*Derivative(y(t), t) - y(t))*exp(t) + Derivative(x(t), (t, 2)),
            t**2*(t*Derivative(x(t), t) - x(t)) + t*(t*Derivative(y(t), t) - y(t)) + Derivative(y(t), (t, 2)))
    sol3 = {'no_of_equation': 2, 'eq': ((t*Derivative(x(t), t) - x(t))*log(t) + (t*Derivative(y(t), t) -
            y(t))*exp(t) + Derivative(x(t), (t, 2)), t**2*(t*Derivative(x(t), t) - x(t)) + t*(t*Derivative(y(t),
            t) - y(t)) + Derivative(y(t), (t, 2))), 'func': [x(t), y(t)], 'order': {x(t): 2, y(t): 2},
            'is_linear': True, 'is_homogeneous': True, 'is_general': True, 'type_of_equation': 'type1', 'A1':
            Matrix([ [-t*log(t), -t*exp(t)], [    -t**3,     -t**2]]), 'is_second_order': True,
            'is_higher_order': True}
    assert _classify_linear_system(eq3, funcs, t) == sol3

    eq4 = (Eq(x2, k*x(t) - l*y1), Eq(y2, l*x1 + k*y(t)))
    sol4 = {'no_of_equation': 2, 'eq': (Eq(Derivative(x(t), (t, 2)), k*x(t) - l*Derivative(y(t), t)),
            Eq(Derivative(y(t), (t, 2)), k*y(t) + l*Derivative(x(t), t))), 'func': [x(t), y(t)], 'order': {x(t):
            2, y(t): 2}, 'is_linear': True, 'is_homogeneous': True, 'is_general': True, 'type_of_equation':
            'type0', 'is_second_order': True, 'is_higher_order': True}
    assert _classify_linear_system(eq4, funcs, t) == sol4


    # Multiple matches

    f, g = symbols("f g", cls=Function)
    y, t_ = symbols("y t_")
    funcs = [f(t), g(t)]

    eq1 = [Eq(Derivative(f(t), t)**2 - 2*Derivative(f(t), t) + 1, 4),
            Eq(-y*f(t) + Derivative(g(t), t), 0)]
    sol1 = {'is_implicit': True,
             'canon_eqs': [[Eq(Derivative(f(t), t), -1), Eq(Derivative(g(t), t), y*f(t))],
              [Eq(Derivative(f(t), t), 3), Eq(Derivative(g(t), t), y*f(t))]]}
    assert _classify_linear_system(eq1, funcs, t) == sol1

    raises(ValueError, lambda: _classify_linear_system(eq1, funcs[:1], t))

    eq2 = [Eq(Derivative(f(t), t), (2*f(t) + g(t) + 1)/t), Eq(Derivative(g(t), t), (f(t) + 2*g(t))/t)]
    sol2 = {'no_of_equation': 2, 'eq': [Eq(Derivative(f(t), t), (2*f(t) + g(t) + 1)/t), Eq(Derivative(g(t), t),
            (f(t) + 2*g(t))/t)], 'func': [f(t), g(t)], 'order': {f(t): 1, g(t): 1}, 'is_linear': True,
            'is_homogeneous': False, 'is_general': True, 'rhs': Matrix([ [1], [0]]), 'func_coeff': Matrix([ [2,
            1], [1, 2]]), 'is_constant': False, 'type_of_equation': 'type6', 't_': t_, 'tau': log(t),
            'commutative_antiderivative': Matrix([ [2*log(t),   log(t)], [  log(t), 2*log(t)]])}
    assert _classify_linear_system(eq2, funcs, t) == sol2

    eq3 = [Eq(Derivative(f(t), t), (2*f(t) + g(t))/t), Eq(Derivative(g(t), t), (f(t) + 2*g(t))/t)]
    sol3 = {'no_of_equation': 2, 'eq': [Eq(Derivative(f(t), t), (2*f(t) + g(t))/t), Eq(Derivative(g(t), t),
            (f(t) + 2*g(t))/t)], 'func': [f(t), g(t)], 'order': {f(t): 1, g(t): 1}, 'is_linear': True,
            'is_homogeneous': True, 'is_general': True, 'func_coeff': Matrix([ [2, 1], [1, 2]]), 'is_constant':
            False, 'type_of_equation': 'type5', 't_': t_, 'rhs': Matrix([ [0], [0]]), 'tau': log(t),
            'commutative_antiderivative': Matrix([ [2*log(t),   log(t)], [  log(t), 2*log(t)]])}
    assert _classify_linear_system(eq3, funcs, t) == sol3


def test_matrix_exp():
    from sympy.matrices.dense import Matrix, eye, zeros
    from sympy.solvers.ode.systems import matrix_exp
    t = Symbol('t')

    for n in range(1, 6+1):
        assert matrix_exp(zeros(n), t) == eye(n)

    for n in range(1, 6+1):
        A = eye(n)
        expAt = exp(t) * eye(n)
        assert matrix_exp(A, t) == expAt

    for n in range(1, 6+1):
        A = Matrix(n, n, lambda i,j: i+1 if i==j else 0)
        expAt = Matrix(n, n, lambda i,j: exp((i+1)*t) if i==j else 0)
        assert matrix_exp(A, t) == expAt

    A = Matrix([[0, 1], [-1, 0]])
    expAt = Matrix([[cos(t), sin(t)], [-sin(t), cos(t)]])
    assert matrix_exp(A, t) == expAt

    A = Matrix([[2, -5], [2, -4]])
    expAt = Matrix([
            [3*exp(-t)*sin(t) + exp(-t)*cos(t), -5*exp(-t)*sin(t)],
            [2*exp(-t)*sin(t), -3*exp(-t)*sin(t) + exp(-t)*cos(t)]
            ])
    assert matrix_exp(A, t) == expAt

    A = Matrix([[21, 17, 6], [-5, -1, -6], [4, 4, 16]])
    # TO update this.
    # expAt = Matrix([
    #     [(8*t*exp(12*t) + 5*exp(12*t) - 1)*exp(4*t)/4,
    #      (8*t*exp(12*t) + 5*exp(12*t) - 5)*exp(4*t)/4,
    #      (exp(12*t) - 1)*exp(4*t)/2],
    #     [(-8*t*exp(12*t) - exp(12*t) + 1)*exp(4*t)/4,
    #      (-8*t*exp(12*t) - exp(12*t) + 5)*exp(4*t)/4,
    #      (-exp(12*t) + 1)*exp(4*t)/2],
    #     [4*t*exp(16*t), 4*t*exp(16*t), exp(16*t)]])
    expAt = Matrix([
        [2*t*exp(16*t) + 5*exp(16*t)/4 - exp(4*t)/4, 2*t*exp(16*t) + 5*exp(16*t)/4 - 5*exp(4*t)/4,  exp(16*t)/2 - exp(4*t)/2],
        [ -2*t*exp(16*t) - exp(16*t)/4 + exp(4*t)/4,  -2*t*exp(16*t) - exp(16*t)/4 + 5*exp(4*t)/4, -exp(16*t)/2 + exp(4*t)/2],
        [                             4*t*exp(16*t),                                4*t*exp(16*t),                 exp(16*t)]
        ])
    assert matrix_exp(A, t) == expAt

    A = Matrix([[1, 1, 0, 0],
                [0, 1, 1, 0],
                [0, 0, 1, -S(1)/8],
                [0, 0, S(1)/2, S(1)/2]])
    expAt = Matrix([
        [exp(t), t*exp(t), 4*t*exp(3*t/4) + 8*t*exp(t) + 48*exp(3*t/4) - 48*exp(t),
                            -2*t*exp(3*t/4) - 2*t*exp(t) - 16*exp(3*t/4) + 16*exp(t)],
        [0, exp(t), -t*exp(3*t/4) - 8*exp(3*t/4) + 8*exp(t), t*exp(3*t/4)/2 + 2*exp(3*t/4) - 2*exp(t)],
        [0, 0, t*exp(3*t/4)/4 + exp(3*t/4), -t*exp(3*t/4)/8],
        [0, 0, t*exp(3*t/4)/2, -t*exp(3*t/4)/4 + exp(3*t/4)]
        ])
    assert matrix_exp(A, t) == expAt

    A = Matrix([
    [ 0, 1,  0, 0],
    [-1, 0,  0, 0],
    [ 0, 0,  0, 1],
    [ 0, 0, -1, 0]])

    expAt = Matrix([
    [ cos(t), sin(t),         0,        0],
    [-sin(t), cos(t),         0,        0],
    [      0,      0,    cos(t),   sin(t)],
    [      0,      0,   -sin(t),   cos(t)]])
    assert matrix_exp(A, t) == expAt

    A = Matrix([
    [ 0, 1,  1, 0],
    [-1, 0,  0, 1],
    [ 0, 0,  0, 1],
    [ 0, 0, -1, 0]])

    expAt = Matrix([
    [ cos(t), sin(t),  t*cos(t), t*sin(t)],
    [-sin(t), cos(t), -t*sin(t), t*cos(t)],
    [      0,      0,    cos(t),   sin(t)],
    [      0,      0,   -sin(t),   cos(t)]])
    assert matrix_exp(A, t) == expAt

    # This case is unacceptably slow right now but should be solvable...
    #a, b, c, d, e, f = symbols('a b c d e f')
    #A = Matrix([
    #[-a,  b,          c,  d],
    #[ a, -b,          e,  0],
    #[ 0,  0, -c - e - f,  0],
    #[ 0,  0,          f, -d]])

    A = Matrix([[0, I], [I, 0]])
    expAt = Matrix([
    [exp(I*t)/2 + exp(-I*t)/2, exp(I*t)/2 - exp(-I*t)/2],
    [exp(I*t)/2 - exp(-I*t)/2, exp(I*t)/2 + exp(-I*t)/2]])
    assert matrix_exp(A, t) == expAt

    # Testing Errors
    M = Matrix([[1, 2, 3], [4, 5, 6], [7, 7, 7]])
    M1 = Matrix([[t, 1], [1, 1]])

    raises(ValueError, lambda: matrix_exp(M[:, :2], t))
    raises(ValueError, lambda: matrix_exp(M[:2, :], t))
    raises(ValueError, lambda: matrix_exp(M1, t))
    raises(ValueError, lambda: matrix_exp(M1[:1, :1], t))


def test_canonical_odes():
    f, g, h = symbols('f g h', cls=Function)
    x = symbols('x')
    funcs = [f(x), g(x), h(x)]

    eqs1 = [Eq(f(x).diff(x, x), f(x) + 2*g(x)), Eq(g(x) + 1, g(x).diff(x) + f(x))]
    sol1 = [[Eq(Derivative(f(x), (x, 2)), f(x) + 2*g(x)), Eq(Derivative(g(x), x), -f(x) + g(x) + 1)]]
    assert canonical_odes(eqs1, funcs[:2], x) == sol1

    eqs2 = [Eq(f(x).diff(x), h(x).diff(x) + f(x)), Eq(g(x).diff(x)**2, f(x) + h(x)), Eq(h(x).diff(x), f(x))]
    sol2 = [[Eq(Derivative(f(x), x), 2*f(x)), Eq(Derivative(g(x), x), -sqrt(f(x) + h(x))), Eq(Derivative(h(x), x), f(x))],
            [Eq(Derivative(f(x), x), 2*f(x)), Eq(Derivative(g(x), x), sqrt(f(x) + h(x))), Eq(Derivative(h(x), x), f(x))]]
    assert canonical_odes(eqs2, funcs, x) == sol2


def test_sysode_linear_neq_order1_type1():

    f, g, x, y, h = symbols('f g x y h', cls=Function)
    a, b, c, t = symbols('a b c t')

    eqs1 = [Eq(Derivative(x(t), t), x(t)),
            Eq(Derivative(y(t), t), y(t))]
    sol1 = [Eq(x(t), C1*exp(t)),
            Eq(y(t), C2*exp(t))]
    assert dsolve(eqs1) == sol1
    assert checksysodesol(eqs1, sol1) == (True, [0, 0])

    eqs2 = [Eq(Derivative(x(t), t), 2*x(t)),
            Eq(Derivative(y(t), t), 3*y(t))]
    sol2 = [Eq(x(t), C1*exp(2*t)),
            Eq(y(t), C2*exp(3*t))]
    assert dsolve(eqs2) == sol2
    assert checksysodesol(eqs2, sol2) == (True, [0, 0])

    eqs3 = [Eq(Derivative(x(t), t), a*x(t)),
            Eq(Derivative(y(t), t), a*y(t))]
    sol3 = [Eq(x(t), C1*exp(a*t)),
            Eq(y(t), C2*exp(a*t))]
    assert dsolve(eqs3) == sol3
    assert checksysodesol(eqs3, sol3) == (True, [0, 0])

    # Regression test case for issue #15474
    # https://github.com/sympy/sympy/issues/15474
    eqs4 = [Eq(Derivative(x(t), t), a*x(t)),
            Eq(Derivative(y(t), t), b*y(t))]
    sol4 = [Eq(x(t), C1*exp(a*t)),
            Eq(y(t), C2*exp(b*t))]
    assert dsolve(eqs4) == sol4
    assert checksysodesol(eqs4, sol4) == (True, [0, 0])

    eqs5 = [Eq(Derivative(x(t), t), -y(t)),
            Eq(Derivative(y(t), t), x(t))]
    sol5 = [Eq(x(t), C1*sin(t) - C2*cos(t)),
            Eq(y(t), -C1*cos(t) - C2*sin(t))]
    assert dsolve(eqs5) == sol5
    assert checksysodesol(eqs5, sol5) == (True, [0, 0])

    eqs6 = [Eq(Derivative(x(t), t), -2*y(t)),
            Eq(Derivative(y(t), t), 2*x(t))]
    sol6 = [Eq(x(t), 2*C1*sin(2*t) - 2*C2*cos(2*t)),
            Eq(y(t), -2*C1*cos(2*t) - 2*C2*sin(2*t))]
    assert dsolve(eqs6) == sol6
    assert checksysodesol(eqs6, sol6) == (True, [0, 0])

    eqs7 = [Eq(Derivative(x(t), t), I*y(t)),
            Eq(Derivative(y(t), t), I*x(t))]
    sol7 = [Eq(x(t), -C1*exp(-I*t) + C2*exp(I*t)),
            Eq(y(t), C1*exp(-I*t) + C2*exp(I*t))]
    assert dsolve(eqs7) == sol7
    assert checksysodesol(eqs7, sol7) == (True, [0, 0])

    eqs8 = [Eq(Derivative(x(t), t), -a*y(t)),
            Eq(Derivative(y(t), t), a*x(t))]
    sol8 = [Eq(x(t), -I*C1*exp(-I*a*t) + I*C2*exp(I*a*t)),
            Eq(y(t), C1*exp(-I*a*t) + C2*exp(I*a*t))]
    assert dsolve(eqs8) == sol8
    assert checksysodesol(eqs8, sol8) == (True, [0, 0])

    eqs9 = [Eq(Derivative(x(t), t), x(t) + y(t)),
            Eq(Derivative(y(t), t), x(t) - y(t))]
    sol9 = [Eq(x(t), C1*exp(-sqrt(2)*t) + C2*exp(sqrt(2)*t)),
            Eq(y(t), -C1*(1 + sqrt(2))*exp(-sqrt(2)*t) - C2*(1 - sqrt(2))*exp(sqrt(2)*t))]
    assert dsolve(eqs9) == sol9
    assert checksysodesol(eqs9, sol9) == (True, [0, 0])

    eqs10 = [Eq(Derivative(x(t), t), x(t) + y(t)),
             Eq(Derivative(y(t), t), x(t) + y(t))]
    sol10 = [Eq(x(t), -C1 + C2*exp(2*t)),
             Eq(y(t), C1 + C2*exp(2*t))]
    assert dsolve(eqs10) == sol10
    assert checksysodesol(eqs10, sol10) == (True, [0, 0])

    eqs11 = [Eq(Derivative(x(t), t), 2*x(t) + y(t)),
             Eq(Derivative(y(t), t), -x(t) + 2*y(t))]
    sol11 = [Eq(x(t), -C1*exp(2*t)*sin(t) + C2*exp(2*t)*cos(t)),
             Eq(y(t), -C1*exp(2*t)*cos(t) - C2*exp(2*t)*sin(t))]
    assert dsolve(eqs11) == sol11
    assert checksysodesol(eqs11, sol11) == (True, [0, 0])

    eqs12 = [Eq(Derivative(x(t), t), x(t) + 2*y(t)),
             Eq(Derivative(y(t), t), 2*x(t) + y(t))]
    sol12 = [Eq(x(t), -2*C1*exp(-t) + 2*C2*exp(3*t)),
             Eq(y(t), 2*C1*exp(-t) + 2*C2*exp(3*t))]
    assert dsolve(eqs12) == sol12
    assert checksysodesol(eqs12, sol12) == (True, [0, 0])

    eqs13 = [Eq(Derivative(x(t), t), 4*x(t) + y(t)),
             Eq(Derivative(y(t), t), -x(t) + 2*y(t))]
    sol13 = [Eq(x(t), C2*t*exp(3*t) + (C1 + C2)*exp(3*t)),
             Eq(y(t), -C1*exp(3*t) - C2*t*exp(3*t))]
    assert dsolve(eqs13) == sol13
    assert checksysodesol(eqs13, sol13) == (True, [0, 0])

    eqs14 = [Eq(Derivative(x(t), t), a*y(t)),
             Eq(Derivative(y(t), t), a*x(t))]
    sol14 = [Eq(x(t), -C1*exp(-a*t) + C2*exp(a*t)),
             Eq(y(t), C1*exp(-a*t) + C2*exp(a*t))]
    assert dsolve(eqs14) == sol14
    assert checksysodesol(eqs14, sol14) == (True, [0, 0])

    eqs15 = [Eq(Derivative(x(t), t), a*y(t)),
             Eq(Derivative(y(t), t), b*x(t))]
    sol15 = [Eq(x(t), -C1*a*exp(-t*sqrt(a*b))/sqrt(a*b) + C2*a*exp(t*sqrt(a*b))/sqrt(a*b)),
             Eq(y(t), C1*exp(-t*sqrt(a*b)) + C2*exp(t*sqrt(a*b)))]
    assert dsolve(eqs15) == sol15
    assert checksysodesol(eqs15, sol15) == (True, [0, 0])

    eqs16 = [Eq(Derivative(x(t), t), a*x(t) + b*y(t)),
             Eq(Derivative(y(t), t), c*x(t))]
    sol16 = [Eq(x(t), -2*C1*b*exp(t*(a + sqrt(a**2 + 4*b*c))/2)/(a - sqrt(a**2 + 4*b*c)) - 2*C2*b*exp(t*(a -
              sqrt(a**2 + 4*b*c))/2)/(a + sqrt(a**2 + 4*b*c))),
             Eq(y(t), C1*exp(t*(a + sqrt(a**2 + 4*b*c))/2) + C2*exp(t*(a - sqrt(a**2 + 4*b*c))/2))]
    assert dsolve(eqs16) == sol16
    assert checksysodesol(eqs16, sol16) == (True, [0, 0])

    # Regression test case for issue #18562
    # https://github.com/sympy/sympy/issues/18562
    eqs17 = [Eq(Derivative(x(t), t), a*y(t) + x(t)),
            Eq(Derivative(y(t), t), a*x(t) - y(t))]
    sol17 = [Eq(x(t), C1*a*exp(t*sqrt(a**2 + 1))/(sqrt(a**2 + 1) - 1) - C2*a*exp(-t*sqrt(a**2 + 1))/(sqrt(a**2 +
              1) + 1)),
            Eq(y(t), C1*exp(t*sqrt(a**2 + 1)) + C2*exp(-t*sqrt(a**2 + 1)))]
    assert dsolve(eqs17) == sol17
    assert checksysodesol(eqs17, sol17) == (True, [0, 0])

    eqs18 = [Eq(Derivative(x(t), t), 0),
            Eq(Derivative(y(t), t), 0)]
    sol18 = [Eq(x(t), C1),
            Eq(y(t), C2)]
    assert dsolve(eqs18) == sol18
    assert checksysodesol(eqs18, sol18) == (True, [0, 0])

    eqs19 = [Eq(Derivative(x(t), t), 2*x(t) - y(t)),
            Eq(Derivative(y(t), t), x(t))]
    sol19 = [Eq(x(t), C2*t*exp(t) + (C1 + C2)*exp(t)),
            Eq(y(t), C1*exp(t) + C2*t*exp(t))]
    assert dsolve(eqs19) == sol19
    assert checksysodesol(eqs19, sol19) == (True, [0, 0])

    eqs20 = [Eq(Derivative(x(t), t), x(t)),
            Eq(Derivative(y(t), t), x(t) + y(t))]
    sol20 = [Eq(x(t), C1*exp(t)),
            Eq(y(t), C1*t*exp(t) + C2*exp(t))]
    assert dsolve(eqs20) == sol20
    assert checksysodesol(eqs20, sol20) == (True, [0, 0])

    eqs21 = [Eq(Derivative(x(t), t), 3*x(t)),
            Eq(Derivative(y(t), t), x(t) + y(t))]
    sol21 = [Eq(x(t), 2*C1*exp(3*t)),
            Eq(y(t), C1*exp(3*t) + 2*C2*exp(t))]
    assert dsolve(eqs21) == sol21
    assert checksysodesol(eqs21, sol21) == (True, [0, 0])

    eqs22 = [Eq(Derivative(x(t), t), 3*x(t)),
            Eq(Derivative(y(t), t), y(t))]
    sol22 = [Eq(x(t), 2*C1*exp(3*t)),
            Eq(y(t), 2*C2*exp(t))]
    assert dsolve(eqs22) == sol22
    assert checksysodesol(eqs22, sol22) == (True, [0, 0])


@slow
def test_sysode_linear_neq_order1_type1_slow():

    t = Symbol('t')
    Z0 = Function('Z0')
    Z1 = Function('Z1')
    Z2 = Function('Z2')
    Z3 = Function('Z3')

    k01, k10, k20, k21, k23, k30 = symbols('k01 k10 k20 k21 k23 k30')

    eqs1 = [Eq(Derivative(Z0(t), t), -k01*Z0(t) + k10*Z1(t) + k20*Z2(t) + k30*Z3(t)),
            Eq(Derivative(Z1(t), t), k01*Z0(t) - k10*Z1(t) + k21*Z2(t)),
            Eq(Derivative(Z2(t), t), (-k20 - k21 - k23)*Z2(t)),
            Eq(Derivative(Z3(t), t), k23*Z2(t) - k30*Z3(t))]
    sol1 = [Eq(Z0(t), C1*k10/k01 - C2*(k10 - k30)*exp(-k30*t)/(k01 + k10 - k30) - C3*(k10*(k20 + k21 - k30) -
             k20**2 - k20*(k21 + k23 - k30) + k23*k30)*exp(-t*(k20 + k21 + k23))/(k23*(-k01 - k10 + k20 + k21 +
             k23)) - C4*exp(-t*(k01 + k10))),
            Eq(Z1(t), C1 - C2*k01*exp(-k30*t)/(k01 + k10 - k30) + C3*(-k01*(k20 + k21 - k30) + k20*k21 + k21**2
             + k21*(k23 - k30))*exp(-t*(k20 + k21 + k23))/(k23*(-k01 - k10 + k20 + k21 + k23)) + C4*exp(-t*(k01 +
             k10))),
            Eq(Z2(t), -C3*(k20 + k21 + k23 - k30)*exp(-t*(k20 + k21 + k23))/k23),
            Eq(Z3(t), C2*exp(-k30*t) + C3*exp(-t*(k20 + k21 + k23)))]
    assert dsolve(eqs1) == sol1
    assert checksysodesol(eqs1, sol1) == (True, [0, 0, 0, 0])

    x, y, z, u, v, w = symbols('x y z u v w', cls=Function)
    k2, k3 = symbols('k2 k3')
    a_b, a_c = symbols('a_b a_c', real=True)

    eqs2 = [Eq(Derivative(z(t), t), k2*y(t)),
            Eq(Derivative(x(t), t), k3*y(t)),
            Eq(Derivative(y(t), t), (-k2 - k3)*y(t))]
    sol2 = [Eq(z(t), C1 - C2*k2*exp(-t*(k2 + k3))/(k2 + k3)),
            Eq(x(t), -C2*k3*exp(-t*(k2 + k3))/(k2 + k3) + C3),
            Eq(y(t), C2*exp(-t*(k2 + k3)))]
    assert dsolve(eqs2) == sol2
    assert checksysodesol(eqs2, sol2) == (True, [0, 0, 0])

    eqs3 = [4*u(t) - v(t) - 2*w(t) + Derivative(u(t), t),
            2*u(t) + v(t) - 2*w(t) + Derivative(v(t), t),
            5*u(t) + v(t) - 3*w(t) + Derivative(w(t), t)]
    sol3 = [Eq(u(t), 7*C3*exp(-2*t) + (4*C1 - 2*sqrt(3)*C2)*cos(sqrt(3)*t) - (2*sqrt(3)*C1 + 4*C2)
               *sin(sqrt(3)*t)), Eq(v(t), (4*C1 - 2*sqrt(3)*C2)*cos(sqrt(3)*t)
                - (2*sqrt(3)*C1 + 4*C2)*sin(sqrt(3)*t)), Eq(w(t), 7*C3*exp(-2*t)
                + (3*C1 - 5*sqrt(3)*C2)*cos(sqrt(3)*t) - (5*sqrt(3)*C1 + 3*C2)*sin(sqrt(3)*t))]
    assert dsolve(eqs3) == sol3
    assert checksysodesol(eqs3, sol3) == (True, [0, 0, 0])

    eqs4 = [Eq(Derivative(x(t), t), w(t)*Rational(-2, 9) + 2*x(t) + y(t) + z(t)*Rational(-8, 9)),
            Eq(Derivative(y(t), t), w(t)*Rational(4, 9) + 2*y(t) + z(t)*Rational(16, 9)),
            Eq(Derivative(z(t), t), w(t)*Rational(-2, 9) + z(t)*Rational(37, 9)),
            Eq(Derivative(w(t), t), w(t)*Rational(44, 9) + z(t)*Rational(-4, 9))]
    sol4 = [Eq(x(t), 8*C1*exp(2*t) + 8*C2*t*exp(2*t)),
            Eq(y(t), 8*C2*exp(2*t) + 8*C3*exp(4*t)/9),
            Eq(z(t), 8*C3*exp(4*t)/9 - 2*C4*exp(5*t)),
            Eq(w(t), 4*C3*exp(4*t)/9 + 8*C4*exp(5*t))]
    assert dsolve(eqs4) == sol4
    assert checksysodesol(eqs4, sol4) == (True, [0, 0, 0, 0])

    # Regression test case for issue #15574
    # https://github.com/sympy/sympy/issues/15574
    eq5 = [Eq(x(t).diff(t), x(t)), Eq(y(t).diff(t), y(t)), Eq(z(t).diff(t), z(t)), Eq(w(t).diff(t), w(t))]
    sol5 = [Eq(x(t), C1*exp(t)), Eq(y(t), C2*exp(t)), Eq(z(t), C3*exp(t)), Eq(w(t), C4*exp(t))]
    assert dsolve(eq5) == sol5
    assert checksysodesol(eq5, sol5) == (True, [0, 0, 0, 0])

    eqs6 = [Eq(Derivative(x(t), t), x(t) + y(t)),
            Eq(Derivative(y(t), t), y(t) + z(t)),
            Eq(Derivative(z(t), t), w(t)*Rational(-1, 8) + z(t)),
            Eq(Derivative(w(t), t), w(t)/2 + z(t)/2)]
    sol6 = [Eq(x(t), C2*t*exp(3*t/4)/64 + C3*exp(t)/16 + C4*t*exp(t)/16 + (C1/64 + 3*C2/16)*exp(3*t/4)),
            Eq(y(t), -C2*t*exp(3*t/4)/256 + C4*exp(t)/16 - (C1/256 + C2/32)*exp(3*t/4)),
            Eq(z(t), C2*t*exp(3*t/4)/1024 + (C1/1024 + C2/256)*exp(3*t/4)),
            Eq(w(t), C1*exp(3*t/4)/512 + C2*t*exp(3*t/4)/512)]
    assert dsolve(eqs6) == sol6
    assert checksysodesol(eqs6, sol6) == (True, [0, 0, 0, 0])

    # Regression test case for issue #15574
    # https://github.com/sympy/sympy/issues/15574
    eq7 = [Eq(Derivative(x(t), t), x(t)), Eq(Derivative(y(t), t), y(t)), Eq(Derivative(z(t), t), z(t)),
           Eq(Derivative(w(t), t), w(t)), Eq(Derivative(u(t), t), u(t))]
    sol7 = [Eq(x(t), C1*exp(t)), Eq(y(t), C2*exp(t)), Eq(z(t), C3*exp(t)), Eq(w(t), C4*exp(t)),
            Eq(u(t), C5*exp(t))]
    assert dsolve(eq7) == sol7
    assert checksysodesol(eq7, sol7) == (True, [0, 0, 0, 0, 0])

    eqs8 = [Eq(Derivative(x(t), t), 2*x(t) + y(t)),
            Eq(Derivative(y(t), t), 2*y(t)),
            Eq(Derivative(z(t), t), 4*z(t)),
            Eq(Derivative(w(t), t), u(t) + 5*w(t)),
            Eq(Derivative(u(t), t), 5*u(t))]
    sol8 = [Eq(x(t), 324*C1*exp(2*t) + 324*C2*t*exp(2*t)),
            Eq(y(t), 324*C2*exp(2*t)), Eq(z(t), 4*C3*exp(4*t)),
            Eq(w(t), 81*C4*exp(5*t) + 81*C5*t*exp(5*t)),
            Eq(u(t), 81*C5*exp(5*t))]
    assert dsolve(eqs8) == sol8
    assert checksysodesol(eqs8, sol8) == (True, [0, 0, 0, 0, 0])

    # Regression test case for issue #15574
    # https://github.com/sympy/sympy/issues/15574
    eq9 = [Eq(Derivative(x(t), t), x(t)), Eq(Derivative(y(t), t), y(t)), Eq(Derivative(z(t), t), z(t))]
    sol9 = [Eq(x(t), C1*exp(t)), Eq(y(t), C2*exp(t)), Eq(z(t), C3*exp(t))]
    assert dsolve(eq9) == sol9
    assert checksysodesol(eq9, sol9) == (True, [0, 0, 0])

    # Regression test case for issue #15407
    # https://github.com/sympy/sympy/issues/15407
    eqs10 = [Eq(Derivative(x(t), t), (-a_b - a_c)*x(t)),
             Eq(Derivative(y(t), t), a_b*y(t)),
             Eq(Derivative(z(t), t), a_c*x(t))]
    sol10 = [Eq(x(t), -C1*(a_b + a_c)*exp(-t*(a_b + a_c))/a_c),
             Eq(y(t), C2*exp(a_b*t)),
             Eq(z(t), C1*exp(-t*(a_b + a_c)) + C3)]
    assert dsolve(eqs10) == sol10
    assert checksysodesol(eqs10, sol10) == (True, [0, 0, 0])

    # Regression test case for issue #14312
    # https://github.com/sympy/sympy/issues/14312
    eqs11 = [Eq(Derivative(x(t), t), k3*y(t)),
             Eq(Derivative(y(t), t), (-k2 - k3)*y(t)),
             Eq(Derivative(z(t), t), k2*y(t))]
    sol11 = [Eq(x(t), C1 + C2*k3*exp(-t*(k2 + k3))/k2),
             Eq(y(t), -C2*(k2 + k3)*exp(-t*(k2 + k3))/k2),
             Eq(z(t), C2*exp(-t*(k2 + k3)) + C3)]
    assert dsolve(eqs11) == sol11
    assert checksysodesol(eqs11, sol11) == (True, [0, 0, 0])

    # Regression test case for issue #14312
    # https://github.com/sympy/sympy/issues/14312
    eqs12 = [Eq(Derivative(z(t), t), k2*y(t)),
             Eq(Derivative(x(t), t), k3*y(t)),
             Eq(Derivative(y(t), t), (-k2 - k3)*y(t))]
    sol12 = [Eq(z(t), C1 - C2*k2*exp(-t*(k2 + k3))/(k2 + k3)),
             Eq(x(t), -C2*k3*exp(-t*(k2 + k3))/(k2 + k3) + C3),
             Eq(y(t), C2*exp(-t*(k2 + k3)))]
    assert dsolve(eqs12) == sol12
    assert checksysodesol(eqs12, sol12) == (True, [0, 0, 0])

    f, g, h = symbols('f, g, h', cls=Function)
    a, b, c = symbols('a, b, c')

    # Regression test case for issue #15474
    # https://github.com/sympy/sympy/issues/15474
    eqs13 = [Eq(Derivative(f(t), t), 2*f(t) + g(t)),
             Eq(Derivative(g(t), t), a*f(t))]
    sol13 = [Eq(f(t), C1*exp(t*(sqrt(a + 1) + 1))/(sqrt(a + 1) - 1) - C2*exp(-t*(sqrt(a + 1) - 1))/(sqrt(a + 1) +
              1)),
             Eq(g(t), C1*exp(t*(sqrt(a + 1) + 1)) + C2*exp(-t*(sqrt(a + 1) - 1)))]
    assert dsolve(eqs13) == sol13
    assert checksysodesol(eqs13, sol13) == (True, [0, 0])

    eqs14 = [Eq(Derivative(f(t), t), 2*g(t) - 3*h(t)),
             Eq(Derivative(g(t), t), -2*f(t) + 4*h(t)),
             Eq(Derivative(h(t), t), 3*f(t) - 4*g(t))]
    sol14 = [Eq(f(t), 16*C1 - (8*C2 + 3*sqrt(29)*C3)*cos(sqrt(29)*t) - (3*sqrt(29)*C2 - 8*C3)*sin(sqrt(29)*t)),
             Eq(g(t), 12*C1 - (6*C2 - 4*sqrt(29)*C3)*cos(sqrt(29)*t) + (4*sqrt(29)*C2 + 6*C3)*sin(sqrt(29)*t)),
             Eq(h(t), 8*C1 + 25*C2*cos(sqrt(29)*t) - 25*C3*sin(sqrt(29)*t))]
    assert dsolve(eqs14) == sol14
    assert checksysodesol(eqs14, sol14) == (True, [0, 0, 0])

    eqs15 = [Eq(2*Derivative(f(t), t), 12*g(t) - 12*h(t)),
             Eq(3*Derivative(g(t), t), -8*f(t) + 8*h(t)),
             Eq(4*Derivative(h(t), t), 6*f(t) - 6*g(t))]
    sol15 = [Eq(f(t), 4*C1 - (16*C2 + 6*sqrt(29)*C3)*cos(sqrt(29)*t)
                - (6*sqrt(29)*C2 - 16*C3)*sin(sqrt(29)*t)),
             Eq(g(t), 4*C1 - (16*C2 - 8*sqrt(29)*C3/3)*cos(sqrt(29)*t)
                + (8*sqrt(29)*C2/3 + 16*C3)*sin(sqrt(29)*t)),
             Eq(h(t), 4*C1 + 13*C2*cos(sqrt(29)*t) - 13*C3*sin(sqrt(29)*t))]
    assert dsolve(eqs15) == sol15
    assert checksysodesol(eqs15, sol15) == (True, [0, 0, 0])

    eq16 = (Eq(diff(x(t), t), 21*x(t)), Eq(diff(y(t), t), 17*x(t) + 3*y(t)),
            Eq(diff(z(t), t), 5*x(t) + 7*y(t) + 9*z(t)))
    sol16 = [Eq(x(t), 216*C1*exp(21*t)),
             Eq(y(t), 204*C1*exp(21*t) - 108*C2*exp(3*t)),
             Eq(z(t), 209*C1*exp(21*t) + 126*C2*exp(3*t) + 72*C3*exp(9*t))]
    assert dsolve(eq16) == sol16
    assert checksysodesol(eq16, sol16) == (True, [0, 0, 0])

    eqs17 = [Eq(Derivative(x(t), t), 3*y(t) - 11*z(t)),
             Eq(Derivative(y(t), t), -3*x(t) + 7*z(t)),
             Eq(Derivative(z(t), t), 11*x(t) - 7*y(t))]
    sol17 = [Eq(x(t), 49*C1 - (21*C2 + 11*sqrt(179)*C3)*cos(sqrt(179)*t)
                - (11*sqrt(179)*C2 - 21*C3)*sin(sqrt(179)*t)),
             Eq(y(t), 77*C1 - (33*C2 - 7*sqrt(179)*C3)*cos(sqrt(179)*t)
                + (7*sqrt(179)*C2 + 33*C3)*sin(sqrt(179)*t)),
             Eq(z(t), 21*C1 + 170*C2*cos(sqrt(179)*t) - 170*C3*sin(sqrt(179)*t))]
    assert dsolve(eqs17) == sol17
    assert checksysodesol(eqs17, sol17) == (True, [0, 0, 0])

    eqs18 = [Eq(3*Derivative(x(t), t), 20*y(t) - 20*z(t)),
             Eq(4*Derivative(y(t), t), -15*x(t) + 15*z(t)),
             Eq(5*Derivative(z(t), t), 12*x(t) - 12*y(t))]
    sol18 = [Eq(x(t), 9*C1 - (25*C2 + 100*sqrt(2)*C3/3)*cos(5*sqrt(2)*t)
                - (100*sqrt(2)*C2/3 - 25*C3)*sin(5*sqrt(2)*t)),
             Eq(y(t), 9*C1 - (25*C2 - 75*sqrt(2)*C3/4)*cos(5*sqrt(2)*t)
                + (75*sqrt(2)*C2/4 + 25*C3)*sin(5*sqrt(2)*t)),
             Eq(z(t), 9*C1 + 25*C2*cos(5*sqrt(2)*t) - 25*C3*sin(5*sqrt(2)*t))]
    assert dsolve(eqs18) == sol18
    assert checksysodesol(eqs18, sol18) == (True, [0, 0, 0])

    eqs19 = [Eq(Derivative(x(t), t), 4*x(t) - z(t)),
             Eq(Derivative(y(t), t), 2*x(t) + 2*y(t) - z(t)),
             Eq(Derivative(z(t), t), 3*x(t) + y(t))]
    sol19 = [Eq(x(t), C2*t**2*exp(2*t)/2 + t*(2*C2 + C3)*exp(2*t) + (C1 + C2 + 2*C3)*exp(2*t)),
             Eq(y(t), C2*t**2*exp(2*t)/2 + t*(2*C2 + C3)*exp(2*t) + (C1 + 2*C3)*exp(2*t)),
             Eq(z(t), C2*t**2*exp(2*t) + t*(3*C2 + 2*C3)*exp(2*t) + (2*C1 + 3*C3)*exp(2*t))]
    assert dsolve(eqs19) == sol19
    assert checksysodesol(eqs19, sol19) == (True, [0, 0, 0])

    eqs20 = [Eq(Derivative(x(t), t), 4*x(t) - y(t) - 2*z(t)),
             Eq(Derivative(y(t), t), 2*x(t) + y(t) - 2*z(t)),
             Eq(Derivative(z(t), t), 5*x(t) - 3*z(t))]
    sol20 = [Eq(x(t), 5*C1*exp(2*t) - (2*C2 - 4*C3)*sin(t) - (4*C2 + 2*C3)*cos(t)),
             Eq(y(t), Mul(-1, (2*C2 - 4*C3), evaluate=False)*sin(t) - (4*C2 + 2*C3)*cos(t)),
             Eq(z(t), 5*C1*exp(2*t)- (5*C2 - 5*C3)*sin(t) - (5*C2 + 5*C3)*cos(t))]
    assert dsolve(eqs20) == sol20
    assert checksysodesol(eqs20, sol20) == (True, [0, 0, 0])

    eq21 = (Eq(diff(x(t), t), 9*y(t)), Eq(diff(y(t), t), 12*x(t)))
    sol21 = [Eq(x(t), 9*C1*exp(-6*sqrt(3)*t) + 9*C2*exp(6*sqrt(3)*t)),
             Eq(y(t), -6*sqrt(3)*C1*exp(-6*sqrt(3)*t) + 6*sqrt(3)*C2*exp(6*sqrt(3)*t))]

    assert dsolve(eq21) == sol21
    assert checksysodesol(eq21, sol21) == (True, [0, 0])

    eqs22 = [Eq(Derivative(x(t), t), 2*x(t) + 4*y(t)),
             Eq(Derivative(y(t), t), 12*x(t) + 41*y(t))]
    sol22 = [Eq(x(t), 4*C1*exp(t*(43 - sqrt(1713))/2) + 4*C2*exp(t*(sqrt(1713) + 43)/2)),
             Eq(y(t), C1*(39 - sqrt(1713))*exp(t*(43 - sqrt(1713))/2)/2 + C2*(39 + sqrt(1713))
                *exp(t*(sqrt(1713) + 43)/2)/2)]
    assert dsolve(eqs22) == sol22
    assert checksysodesol(eqs22, sol22) == (True, [0, 0])

    eqs23 = [Eq(Derivative(x(t), t), x(t) + y(t)),
             Eq(Derivative(y(t), t), -2*x(t) + 2*y(t))]
    sol23 = [Eq(x(t), -C1*exp(3*t/2)*sin(sqrt(7)*t/2) + C2*exp(3*t/2)*cos(sqrt(7)*t/2)),
             Eq(y(t), Mul(-1, (C1/2 + sqrt(7)*C2/2), evaluate=False)*exp(3*t/2)*sin(sqrt(7)*t/2)
                - (sqrt(7)*C1/2 - C2/2)*exp(3*t/2)*cos(sqrt(7)*t/2))]
    assert dsolve(eqs23) == sol23
    assert checksysodesol(eqs23, sol23) == (True, [0, 0])

    # Regression test case for issue #15474
    # https://github.com/sympy/sympy/issues/15474
    a = Symbol("a", real=True)
    eq24 = [x(t).diff(t) - a*y(t), y(t).diff(t) + a*x(t)]
    sol24 = [Eq(x(t), C1*sin(a*t) + C2*cos(a*t)), Eq(y(t), C1*cos(a*t) - C2*sin(a*t))]
    assert dsolve(eq24) == sol24
    assert checksysodesol(eq24, sol24) == (True, [0, 0])

    # Regression test case for issue #19150
    # https://github.com/sympy/sympy/issues/19150
    eqs25 = [Eq(Derivative(f(t), t), 0),
             Eq(Derivative(g(t), t), (f(t) - 2*g(t) + x(t))/(b*c)),
             Eq(Derivative(x(t), t), (g(t) - 2*x(t) + y(t))/(b*c)),
             Eq(Derivative(y(t), t), (h(t) + x(t) - 2*y(t))/(b*c)),
             Eq(Derivative(h(t), t), 0)]
    sol25 = [Eq(f(t), -3*C1 + 4*C2),
             Eq(g(t), -2*C1 + 3*C2 - C3*exp(-2*t/(b*c)) + C4*exp(-t*(sqrt(2) + 2)/(b*c)) + C5*exp(-t*(2 -
              sqrt(2))/(b*c))),
             Eq(x(t), -C1 + 2*C2 - sqrt(2)*C4*exp(-t*(sqrt(2) + 2)/(b*c)) + sqrt(2)*C5*exp(-t*(2 -
              sqrt(2))/(b*c))),
             Eq(y(t), C2 + C3*exp(-2*t/(b*c)) + C4*exp(-t*(sqrt(2) + 2)/(b*c)) + C5*exp(-t*(2 - sqrt(2))/(b*c))),
             Eq(h(t), C1)]
    assert dsolve(eqs25) == sol25
    assert checksysodesol(eqs25, sol25) == (True, [0, 0, 0, 0, 0])

    eq26 = [Eq(Derivative(f(t), t), 2*f(t)), Eq(Derivative(g(t), t), 3*f(t) + 7*g(t))]
    sol26 = [Eq(f(t), -5*C1*exp(2*t)), Eq(g(t), 3*C1*exp(2*t) + 5*C2*exp(7*t))]
    assert dsolve(eq26) == sol26
    assert checksysodesol(eq26, sol26) == (True, [0, 0])

    eq27 = [Eq(Derivative(f(t), t), -9*I*f(t) - 4*g(t)), Eq(Derivative(g(t), t), -4*I*g(t))]
    sol27 = [Eq(f(t), 4*I*C1*exp(-4*I*t)/5 + C2*exp(-9*I*t)), Eq(g(t), C1*exp(-4*I*t))]
    assert dsolve(eq27) == sol27
    assert checksysodesol(eq27, sol27) == (True, [0, 0])

    eq28 = [Eq(Derivative(f(t), t), -9*I*f(t)), Eq(Derivative(g(t), t), -4*I*g(t))]
    sol28 = [Eq(f(t), C1*exp(-9*I*t)), Eq(g(t), C2*exp(-4*I*t))]
    assert dsolve(eq28) == sol28
    assert checksysodesol(eq28, sol28) == (True, [0, 0])

    eq29 = [Eq(Derivative(f(t), t), 0), Eq(Derivative(g(t), t), 0)]
    sol29 = [Eq(f(t), C1), Eq(g(t), C2)]
    assert dsolve(eq29) == sol29
    assert checksysodesol(eq29, sol29) == (True, [0, 0])

    eq30 = [Eq(Derivative(f(t), t), f(t)), Eq(Derivative(g(t), t), 0)]
    sol30 = [Eq(f(t), C1*exp(t)), Eq(g(t), C2)]
    assert dsolve(eq30) == sol30
    assert checksysodesol(eq30, sol30) == (True, [0, 0])

    eq31 = [Eq(Derivative(f(t), t), g(t)), Eq(Derivative(g(t), t), 0)]
    sol31 = [Eq(f(t), C1 + C2*t), Eq(g(t), C2)]
    assert dsolve(eq31) == sol31
    assert checksysodesol(eq31, sol31) == (True, [0, 0])

    eq32 = [Eq(Derivative(f(t), t), 0), Eq(Derivative(g(t), t), f(t))]
    sol32 = [Eq(f(t), C1), Eq(g(t), C1*t + C2)]
    assert dsolve(eq32) == sol32
    assert checksysodesol(eq32, sol32) == (True, [0, 0])

    eq33 = [Eq(Derivative(f(t), t), 0), Eq(Derivative(g(t), t), g(t))]
    sol33 = [Eq(f(t), C1), Eq(g(t), C2*exp(t))]
    assert dsolve(eq33) == sol33
    assert checksysodesol(eq33, sol33) == (True, [0, 0])

    eq34 = [Eq(Derivative(f(t), t), f(t)), Eq(Derivative(g(t), t), I*g(t))]
    sol34 = [Eq(f(t), C1*exp(t)), Eq(g(t), C2*exp(I*t))]
    assert dsolve(eq34) == sol34
    assert checksysodesol(eq34, sol34) == (True, [0, 0])

    eq35 = [Eq(Derivative(f(t), t), I*f(t)), Eq(Derivative(g(t), t), -I*g(t))]
    sol35 = [Eq(f(t), C1*exp(I*t)), Eq(g(t), C2*exp(-I*t))]
    assert dsolve(eq35) == sol35
    assert checksysodesol(eq35, sol35) == (True, [0, 0])

    eq36 = [Eq(Derivative(f(t), t), I*g(t)), Eq(Derivative(g(t), t), 0)]
    sol36 = [Eq(f(t), I*C1 + I*C2*t), Eq(g(t), C2)]
    assert dsolve(eq36) == sol36
    assert checksysodesol(eq36, sol36) == (True, [0, 0])

    eq37 = [Eq(Derivative(f(t), t), I*g(t)), Eq(Derivative(g(t), t), I*f(t))]
    sol37 = [Eq(f(t), -C1*exp(-I*t) + C2*exp(I*t)), Eq(g(t), C1*exp(-I*t) + C2*exp(I*t))]
    assert dsolve(eq37) == sol37
    assert checksysodesol(eq37, sol37) == (True, [0, 0])

    # Multiple systems
    eq1 = [Eq(Derivative(f(t), t)**2, g(t)**2), Eq(-f(t) + Derivative(g(t), t), 0)]
    sol1 = [[Eq(f(t), C1*sin(t) - C2*cos(t)),
             Eq(g(t), -C1*cos(t) - C2*sin(t))],
           [Eq(f(t), -C1*exp(-t) + C2*exp(t)),
              Eq(g(t), C1*exp(-t) + C2*exp(t))]]
    assert dsolve(eq1) == sol1
    for sol in sol1:
        assert checksysodesol(eq1, sol) == (True, [0, 0])


def test_sysode_linear_neq_order1_type2():

    f, g, h, k = symbols('f g h k', cls=Function)
    x, t, a, b, c, d, y = symbols('x t a b c d y')
    k1, k2 = symbols('k1 k2')


    eqs1 = [Eq(Derivative(f(x), x), f(x) + g(x) + 5),
            Eq(Derivative(g(x), x), -f(x) - g(x) + 7)]
    sol1 = [Eq(f(x), C1 + C2 + 6*x**2 + x*(C2 + 5)),
            Eq(g(x), -C1 - 6*x**2 - x*(C2 - 7))]
    assert dsolve(eqs1) == sol1
    assert checksysodesol(eqs1, sol1) == (True, [0, 0])

    eqs2 = [Eq(Derivative(f(x), x), f(x) + g(x) + 5),
            Eq(Derivative(g(x), x), f(x) + g(x) + 7)]
    sol2 = [Eq(f(x), -C1 + C2*exp(2*x) - x - 3),
            Eq(g(x), C1 + C2*exp(2*x) + x - 3)]
    assert dsolve(eqs2) == sol2
    assert checksysodesol(eqs2, sol2) == (True, [0, 0])

    eqs3 = [Eq(Derivative(f(x), x), f(x) + 5),
            Eq(Derivative(g(x), x), f(x) + 7)]
    sol3 = [Eq(f(x), C1*exp(x) - 5),
            Eq(g(x), C1*exp(x) + C2 + 2*x - 5)]
    assert dsolve(eqs3) == sol3
    assert checksysodesol(eqs3, sol3) == (True, [0, 0])

    eqs4 = [Eq(Derivative(f(x), x), f(x) + exp(x)),
            Eq(Derivative(g(x), x), x*exp(x) + f(x) + g(x))]
    sol4 = [Eq(f(x), C1*exp(x) + x*exp(x)),
            Eq(g(x), C1*x*exp(x) + C2*exp(x) + x**2*exp(x))]
    assert dsolve(eqs4) == sol4
    assert checksysodesol(eqs4, sol4) == (True, [0, 0])

    eqs5 = [Eq(Derivative(f(x), x), 5*x + f(x) + g(x)),
            Eq(Derivative(g(x), x), f(x) - g(x))]
    sol5 = [Eq(f(x), C1*exp(-sqrt(2)*x) + C2*exp(sqrt(2)*x) - Rational(5,2)*x - Rational(5,2)),
            Eq(g(x), -C1*(1 + sqrt(2))*exp(-sqrt(2)*x) - C2*(1 - sqrt(2))*exp(sqrt(2)*x) - Rational(5,2)*x)]
    assert dsolve(eqs5) == sol5
    assert checksysodesol(eqs5, sol5) == (True, [0, 0])

    eqs6 = [Eq(Derivative(f(x), x), -9*f(x) - 4*g(x)),
            Eq(Derivative(g(x), x), -4*g(x)),
            Eq(Derivative(h(x), x), h(x) + exp(x))]
    sol6 = [Eq(f(x), 40*C1*exp(-9*x) - 20*C2*exp(-4*x)),
            Eq(g(x), 25*C2*exp(-4*x)),
            Eq(h(x), 50*C3*exp(x) + x*exp(x))]
    assert dsolve(eqs6) == sol6
    assert checksysodesol(eqs6, sol6) == (True, [0, 0, 0])

    # Regression test case for issue #8859
    # https://github.com/sympy/sympy/issues/8859
    eqs7 = [Eq(Derivative(f(t), t), 3*t + f(t)),
            Eq(Derivative(g(t), t), g(t))]
    sol7 = [Eq(f(t), C1*exp(t) - 3*t - 3),
            Eq(g(t), C2*exp(t))]
    assert dsolve(eqs7) == sol7
    assert checksysodesol(eqs7, sol7) == (True, [0, 0])

    # Regression test case for issue #8567
    # https://github.com/sympy/sympy/issues/8567
    eqs8 = [Eq(Derivative(f(t), t), f(t) + 2*g(t)),
            Eq(Derivative(g(t), t), -2*f(t) + g(t) + 2*exp(t))]
    sol8 = [Eq(f(t), -2*C1*exp(t)*sin(2*t) + 2*C2*exp(t)*cos(2*t)+ exp(t)*sin(2*t)**2 + exp(t)*cos(2*t)**2),
            Eq(g(t), -2*C1*exp(t)*cos(2*t) - 2*C2*exp(t)*sin(2*t))]
    assert dsolve(eqs8) == sol8
    assert checksysodesol(eqs8, sol8) == (True, [0, 0])

    # Regression test case for issue #19150
    # https://github.com/sympy/sympy/issues/19150
    eqs9 = [Eq(Derivative(f(t), t), (c - 2*f(t) + g(t))/(a*b)),
            Eq(Derivative(g(t), t), (f(t) - 2*g(t) + h(t))/(a*b)),
            Eq(Derivative(h(t), t), (d + g(t) - 2*h(t))/(a*b))]
    sol9 = [Eq(f(t), -C1*exp(-2*t/(a*b)) + C2*exp(-t*(sqrt(2) + 2)/(a*b)) + C3*exp(-t*(2 - sqrt(2))/(a*b)) +
             Mul(Rational(1, 4), 3*c + d, evaluate=False)),
            Eq(g(t), -sqrt(2)*C2*exp(-t*(sqrt(2) + 2)/(a*b)) + sqrt(2)*C3*exp(-t*(2 - sqrt(2))/(a*b)) +
             Mul(Rational(1, 2), c + d, evaluate=False)),
            Eq(h(t), C1*exp(-2*t/(a*b)) + C2*exp(-t*(sqrt(2) + 2)/(a*b)) + C3*exp(-t*(2 - sqrt(2))/(a*b)) +
             Mul(Rational(1, 4), c + 3*d, evaluate=False))]
    assert dsolve(eqs9) == sol9
    assert checksysodesol(eqs9, sol9) == (True, [0, 0, 0])

    # Regression test case for issue #16635
    # https://github.com/sympy/sympy/issues/16635
    eqs10 = [Eq(Derivative(f(t), t), 15*t + f(t) - g(t) - 10),
             Eq(Derivative(g(t), t), -15*t + f(t) - g(t) - 5)]
    sol10 = [Eq(f(t), C1 + C2 + 5*t**3 + 5*t**2 + t*(C2 - 10)),
             Eq(g(t), C1 + 5*t**3 - 10*t**2 + t*(C2 - 5))]
    assert dsolve(eqs10) == sol10
    assert checksysodesol(eqs10, sol10) == (True, [0, 0])

    # Multiple solutions
    eqs11 = [Eq(Derivative(f(t), t)**2 - 2*Derivative(f(t), t) + 1, 4),
             Eq(-y*f(t) + Derivative(g(t), t), 0)]
    sol11 = [[Eq(f(t), C1 - t), Eq(g(t), C1*t*y + C2*y + t**2*y*Rational(-1, 2))],
             [Eq(f(t), C1 + 3*t), Eq(g(t), C1*t*y + C2*y + t**2*y*Rational(3, 2))]]
    assert dsolve(eqs11) == sol11
    for s11 in sol11:
        assert checksysodesol(eqs11, s11) == (True, [0, 0])

    # test case for issue #19831
    # https://github.com/sympy/sympy/issues/19831
    n = symbols('n', positive=True)
    x0 = symbols('x_0')
    t0 = symbols('t_0')
    x_0 = symbols('x_0')
    t_0 = symbols('t_0')
    t = symbols('t')
    x = Function('x')
    y = Function('y')
    T = symbols('T')

    eqs12 = [Eq(Derivative(y(t), t), x(t)),
             Eq(Derivative(x(t), t), n*(y(t) + 1))]
    sol12 = [Eq(y(t), C1*exp(sqrt(n)*t)*n**Rational(-1, 2) - C2*exp(-sqrt(n)*t)*n**Rational(-1, 2) - 1),
             Eq(x(t), C1*exp(sqrt(n)*t) + C2*exp(-sqrt(n)*t))]
    assert dsolve(eqs12) == sol12
    assert checksysodesol(eqs12, sol12) == (True, [0, 0])

    sol12b = [
        Eq(y(t), (T*exp(-sqrt(n)*t_0)/2 + exp(-sqrt(n)*t_0)/2 +
            x_0*exp(-sqrt(n)*t_0)/(2*sqrt(n)))*exp(sqrt(n)*t) +
            (T*exp(sqrt(n)*t_0)/2 + exp(sqrt(n)*t_0)/2 -
                x_0*exp(sqrt(n)*t_0)/(2*sqrt(n)))*exp(-sqrt(n)*t) - 1),
        Eq(x(t), (T*sqrt(n)*exp(-sqrt(n)*t_0)/2 + sqrt(n)*exp(-sqrt(n)*t_0)/2
            + x_0*exp(-sqrt(n)*t_0)/2)*exp(sqrt(n)*t)
                - (T*sqrt(n)*exp(sqrt(n)*t_0)/2 + sqrt(n)*exp(sqrt(n)*t_0)/2 -
                    x_0*exp(sqrt(n)*t_0)/2)*exp(-sqrt(n)*t))
          ]
    assert dsolve(eqs12, ics={y(t0): T, x(t0): x0}) == sol12b
    assert checksysodesol(eqs12, sol12b) == (True, [0, 0])

    #Test cases added for the issue 19763
    #https://github.com/sympy/sympy/issues/19763

    eq13 = [Eq(Derivative(f(t), t), f(t) + g(t) + 9),
            Eq(Derivative(g(t), t), 2*f(t) + 5*g(t) + 23)]
    sol13 = [Eq(f(t), C1*exp(t*(3 - sqrt(6))) + C2*exp(t*(sqrt(6) + 3)) - Rational(22,3)),
             Eq(g(t), C1*(2 - sqrt(6))*exp(t*(3 - sqrt(6))) + C2*(2 + sqrt(6))*exp(t*(sqrt(6) + 3))
                - Rational(5,3))]
    assert dsolve(eq13) == sol13
    assert checksysodesol(eq13, sol13) == (True, [0, 0])

    eq14 = [Eq(Derivative(f(t), t), f(t) + g(t) + 81),
            Eq(Derivative(g(t), t), -2*f(t) + g(t) + 23)]
    sol14 = [Eq(f(t), -C1*exp(t)*sin(sqrt(2)*t) + C2*exp(t)*cos(sqrt(2)*t)
                - 58*sin(sqrt(2)*t)**2/3 - 58*cos(sqrt(2)*t)**2/3),
             Eq(g(t), -sqrt(2)*C1*exp(t)*cos(sqrt(2)*t) - sqrt(2)*C2*exp(t)*sin(sqrt(2)*t)
                - 185*sin(sqrt(2)*t)**2/3 - 185*cos(sqrt(2)*t)**2/3)]
    assert dsolve(eq14) == sol14
    assert checksysodesol(eq14, sol14) == (True, [0,0])

    eq15 = [Eq(Derivative(f(t), t), f(t) + 2*g(t) + k1),
            Eq(Derivative(g(t), t), 3*f(t) + 4*g(t) + k2)]
    sol15 = [Eq(f(t), 2*C1*exp(t*(5 + sqrt(33))/2) + 2*C2*exp(t*(5 - sqrt(33))/2) + 2*k1 - k2),
             Eq(g(t), C1*(3 + sqrt(33))*exp(t*(5 + sqrt(33))/2)/2
                + C2*(3 - sqrt(33))*exp(t*(5 - sqrt(33))/2)/2
                - Mul(Rational(1,2), 3*k1 - k2, evaluate=False))]
    assert dsolve(eq15) == sol15
    assert checksysodesol(eq15, sol15) == (True, [0,0])

    eq16 = [Eq(Derivative(f(t), t), k1),
            Eq(Derivative(g(t), t), k2)]
    sol16 = [Eq(f(t), C1 + k1*t),
             Eq(g(t), C2 + k2*t)]
    assert dsolve(eq16) == sol16
    assert checksysodesol(eq16, sol16) == (True, [0,0])

    eq17 = [Eq(Derivative(f(t), t), 0),
            Eq(Derivative(g(t), t), c*f(t) + k2)]
    sol17 = [Eq(f(t), C1),
             Eq(g(t), C2*c + t*(C1*c + k2))]
    assert dsolve(eq17) == sol17
    assert checksysodesol(eq17 , sol17) == (True , [0,0])

    eq18 = [Eq(Derivative(f(t), t), k1),
            Eq(Derivative(g(t), t), f(t) + k2)]
    sol18 = [Eq(f(t), C1 + k1*t),
             Eq(g(t), C2 + k1*t**2/2 + t*(C1 + k2))]
    assert dsolve(eq18) == sol18
    assert checksysodesol(eq18 , sol18) == (True , [0,0])

    eq19 = [Eq(Derivative(f(t), t), k1),
            Eq(Derivative(g(t), t), f(t) + 2*g(t) + k2)]
    sol19 = [Eq(f(t), -2*C1 + k1*t),
            Eq(g(t), C1 + 2*C2*exp(2*t) - k1*t/2 - Mul(Rational(1,4), k1 + 2*k2 , evaluate = False))]
    assert dsolve(eq19) == sol19
    assert checksysodesol(eq19 , sol19) == (True , [0,0])

    eq20 = [Eq(diff(f(t), t), f(t) + k1),
            Eq(diff(g(t), t), k2)]
    sol20 = [Eq(f(t), C1*exp(t) - k1),
            Eq(g(t), C2 + k2*t)]
    assert dsolve(eq20) == sol20
    assert checksysodesol(eq20 , sol20) == (True , [0,0])

    eq21 = [Eq(diff(f(t), t), g(t) + k1),
            Eq(diff(g(t), t), 0)]
    sol21 = [Eq(f(t), C1 + t*(C2 + k1)),
            Eq(g(t), C2)]
    assert dsolve(eq21) == sol21
    assert checksysodesol(eq21 , sol21) == (True , [0,0])

    eq22 = [Eq(Derivative(f(t), t), f(t) + 2*g(t) + k1),
            Eq(Derivative(g(t), t), k2)]
    sol22 = [Eq(f(t), -2*C1 + 2*C2*exp(t) - k1 - 2*k2*t - 2*k2),
            Eq(g(t), C1 + k2*t)]
    assert dsolve(eq22) == sol22
    assert checksysodesol(eq22 , sol22) == (True , [0,0])

    eq23 = [Eq(Derivative(f(t), t), g(t) + k1),
            Eq(Derivative(g(t), t), 2*g(t) + k2)]
    sol23 = [Eq(f(t), C1 + C2*exp(2*t) - k2/4 + t*(2*k1 - k2)/2),
            Eq(g(t), 2*C2*exp(2*t) - k2/2)]
    assert dsolve(eq23) == sol23
    assert checksysodesol(eq23 , sol23) == (True , [0,0])

    eq24 = [Eq(Derivative(f(t), t), f(t) + k1),
            Eq(Derivative(g(t), t), 2*f(t) + k2)]
    sol24 = [Eq(f(t), C1*exp(t) - k1),
            Eq(g(t), 2*C1*exp(t) + C2 - 2*k1 - t*(2*k1 - k2))]
    assert dsolve(eq24) == sol24
    assert checksysodesol(eq24 , sol24) == (True , [0,0])

    eq25 = [Eq(Derivative(f(t), t), f(t) + 2*g(t) + k1),
            Eq(Derivative(g(t), t), 3*f(t) + 6*g(t) + k2)]
    sol25 = [Eq(f(t), -2*C1 + 2*C2*exp(7*t) + 2*t*(3*k1 - k2)/7 -
              Mul(Rational(1,49), k1 + 2*k2 , evaluate = False)),
             Eq(g(t), C1 + 6*C2*exp(7*t) - t*(3*k1 - k2)/7 -
              Mul(Rational(3,49), k1 + 2*k2 , evaluate = False))]
    assert dsolve(eq25) == sol25
    assert checksysodesol(eq25 , sol25) == (True , [0,0])

    eq26 = [Eq(Derivative(f(t), t), 2*f(t) - g(t) + k1),
            Eq(Derivative(g(t), t), 4*f(t) - 2*g(t) + 2*k1)]
    sol26 = [Eq(f(t), C1 + 2*C2 + t*(2*C1 + k1)),
            Eq(g(t), 4*C2 + t*(4*C1 + 2*k1))]
    assert dsolve(eq26) == sol26
    assert checksysodesol(eq26 , sol26) == (True , [0,0])

    # Test Case added for issue #22715
    # https://github.com/sympy/sympy/issues/22715

    eq27 = [Eq(diff(x(t),t),-1*y(t)+10), Eq(diff(y(t),t),5*x(t)-2*y(t)+3)]
    sol27 = [Eq(x(t), C1*exp(-t)*sin(2*t) - C2*exp(-t)*cos(2*t) + 17*sin(2*t)**2/5 + 17*cos(2*t)**2/5),
             Eq(y(t), (C1 - 2*C2)*exp(-t)*sin(2*t) - (2*C1 + C2)*exp(-t)*cos(2*t)
                + 10*sin(2*t)**2 + 10*cos(2*t)**2)]
    assert dsolve(eq27) == sol27
    assert checksysodesol(eq27 , sol27) == (True , [0,0])


def test_sysode_linear_neq_order1_type3():

    f, g, h, k, x0 , y0 = symbols('f g h k x0 y0', cls=Function)
    x, t, a = symbols('x t a')
    r = symbols('r', real=True)

    eqs1 = [Eq(Derivative(f(r), r), r*g(r) + f(r)),
            Eq(Derivative(g(r), r), -r*f(r) + g(r))]
    sol1 = [Eq(f(r), C1*exp(r)*sin(r**2/2) + C2*exp(r)*cos(r**2/2)),
            Eq(g(r), C1*exp(r)*cos(r**2/2) - C2*exp(r)*sin(r**2/2))]
    assert dsolve(eqs1) == sol1
    assert checksysodesol(eqs1, sol1) == (True, [0, 0])

    eqs2 = [Eq(Derivative(f(x), x), x**2*g(x) + x*f(x)),
            Eq(Derivative(g(x), x), 2*x**2*f(x) + (3*x**2 + x)*g(x))]
    sol2 = [Eq(f(x), (sqrt(17)*C1/17 + C2*(17 - 3*sqrt(17))/34)*exp(x**3*(3 + sqrt(17))/6 + x**2/2) -
             exp(x**3*(3 - sqrt(17))/6 + x**2/2)*(sqrt(17)*C1/17 + C2*(3*sqrt(17) + 17)*Rational(-1, 34))),
            Eq(g(x), exp(x**3*(3 - sqrt(17))/6 + x**2/2)*(C1*(17 - 3*sqrt(17))/34 + sqrt(17)*C2*Rational(-2,
             17)) + exp(x**3*(3 + sqrt(17))/6 + x**2/2)*(C1*(3*sqrt(17) + 17)/34 + sqrt(17)*C2*Rational(2, 17)))]
    assert dsolve(eqs2) == sol2
    assert checksysodesol(eqs2, sol2) == (True, [0, 0])

    eqs3 = [Eq(f(x).diff(x), x*f(x) + g(x)),
            Eq(g(x).diff(x), -f(x) + x*g(x))]
    sol3 = [Eq(f(x), (C1/2 + I*C2/2)*exp(x**2/2 - I*x) + exp(x**2/2 + I*x)*(C1/2 + I*C2*Rational(-1, 2))),
            Eq(g(x), (I*C1/2 + C2/2)*exp(x**2/2 + I*x) - exp(x**2/2 - I*x)*(I*C1/2 + C2*Rational(-1, 2)))]
    assert dsolve(eqs3) == sol3
    assert checksysodesol(eqs3, sol3) == (True, [0, 0])

    eqs4 = [Eq(f(x).diff(x), x*(f(x) + g(x) + h(x))), Eq(g(x).diff(x), x*(f(x) + g(x) + h(x))),
            Eq(h(x).diff(x), x*(f(x) + g(x) + h(x)))]
    sol4 = [Eq(f(x), -C1/3 - C2/3 + 2*C3/3 + (C1/3 + C2/3 + C3/3)*exp(3*x**2/2)),
            Eq(g(x), 2*C1/3 - C2/3 - C3/3 + (C1/3 + C2/3 + C3/3)*exp(3*x**2/2)),
            Eq(h(x), -C1/3 + 2*C2/3 - C3/3 + (C1/3 + C2/3 + C3/3)*exp(3*x**2/2))]
    assert dsolve(eqs4) == sol4
    assert checksysodesol(eqs4, sol4) == (True, [0, 0, 0])

    eqs5 = [Eq(f(x).diff(x), x**2*(f(x) + g(x) + h(x))), Eq(g(x).diff(x), x**2*(f(x) + g(x) + h(x))),
            Eq(h(x).diff(x), x**2*(f(x) + g(x) + h(x)))]
    sol5 = [Eq(f(x), -C1/3 - C2/3 + 2*C3/3 + (C1/3 + C2/3 + C3/3)*exp(x**3)),
            Eq(g(x), 2*C1/3 - C2/3 - C3/3 + (C1/3 + C2/3 + C3/3)*exp(x**3)),
            Eq(h(x), -C1/3 + 2*C2/3 - C3/3 + (C1/3 + C2/3 + C3/3)*exp(x**3))]
    assert dsolve(eqs5) == sol5
    assert checksysodesol(eqs5, sol5) == (True, [0, 0, 0])

    eqs6 = [Eq(Derivative(f(x), x), x*(f(x) + g(x) + h(x) + k(x))),
            Eq(Derivative(g(x), x), x*(f(x) + g(x) + h(x) + k(x))),
            Eq(Derivative(h(x), x), x*(f(x) + g(x) + h(x) + k(x))),
            Eq(Derivative(k(x), x), x*(f(x) + g(x) + h(x) + k(x)))]
    sol6 = [Eq(f(x), -C1/4 - C2/4 - C3/4 + 3*C4/4 + (C1/4 + C2/4 + C3/4 + C4/4)*exp(2*x**2)),
            Eq(g(x), 3*C1/4 - C2/4 - C3/4 - C4/4 + (C1/4 + C2/4 + C3/4 + C4/4)*exp(2*x**2)),
            Eq(h(x), -C1/4 + 3*C2/4 - C3/4 - C4/4 + (C1/4 + C2/4 + C3/4 + C4/4)*exp(2*x**2)),
            Eq(k(x), -C1/4 - C2/4 + 3*C3/4 - C4/4 + (C1/4 + C2/4 + C3/4 + C4/4)*exp(2*x**2))]
    assert dsolve(eqs6) == sol6
    assert checksysodesol(eqs6, sol6) == (True, [0, 0, 0, 0])

    y = symbols("y", real=True)

    eqs7 = [Eq(Derivative(f(y), y), y*f(y) + g(y)),
            Eq(Derivative(g(y), y), y*g(y) - f(y))]
    sol7 = [Eq(f(y), C1*exp(y**2/2)*sin(y) + C2*exp(y**2/2)*cos(y)),
            Eq(g(y), C1*exp(y**2/2)*cos(y) - C2*exp(y**2/2)*sin(y))]
    assert dsolve(eqs7) == sol7
    assert checksysodesol(eqs7, sol7) == (True, [0, 0])

    #Test cases added for the issue 19763
    #https://github.com/sympy/sympy/issues/19763

    eqs8 = [Eq(Derivative(f(t), t), 5*t*f(t) + 2*h(t)),
            Eq(Derivative(h(t), t), 2*f(t) + 5*t*h(t))]
    sol8 = [Eq(f(t), Mul(-1, (C1/2 - C2/2), evaluate = False)*exp(5*t**2/2 - 2*t) + (C1/2 + C2/2)*exp(5*t**2/2 + 2*t)),
            Eq(h(t), (C1/2 - C2/2)*exp(5*t**2/2 - 2*t) + (C1/2 + C2/2)*exp(5*t**2/2 + 2*t))]
    assert dsolve(eqs8) == sol8
    assert checksysodesol(eqs8, sol8) == (True, [0, 0])

    eqs9 = [Eq(diff(f(t), t), 5*t*f(t) + t**2*g(t)),
            Eq(diff(g(t), t), -t**2*f(t) + 5*t*g(t))]
    sol9 = [Eq(f(t), (C1/2 - I*C2/2)*exp(I*t**3/3 + 5*t**2/2) + (C1/2 + I*C2/2)*exp(-I*t**3/3 + 5*t**2/2)),
            Eq(g(t), Mul(-1, (I*C1/2 - C2/2) , evaluate = False)*exp(-I*t**3/3 + 5*t**2/2) + (I*C1/2 + C2/2)*exp(I*t**3/3 + 5*t**2/2))]
    assert dsolve(eqs9) == sol9
    assert checksysodesol(eqs9 , sol9) == (True , [0,0])

    eqs10 = [Eq(diff(f(t), t), t**2*g(t) + 5*t*f(t)),
             Eq(diff(g(t), t), -t**2*f(t) + (9*t**2 + 5*t)*g(t))]
    sol10 = [Eq(f(t), (C1*(77 - 9*sqrt(77))/154 + sqrt(77)*C2/77)*exp(t**3*(sqrt(77) + 9)/6 + 5*t**2/2) + (C1*(77 + 9*sqrt(77))/154 - sqrt(77)*C2/77)*exp(t**3*(9 - sqrt(77))/6 + 5*t**2/2)),
             Eq(g(t), (sqrt(77)*C1/77 + C2*(77 - 9*sqrt(77))/154)*exp(t**3*(9 - sqrt(77))/6 + 5*t**2/2) - (sqrt(77)*C1/77 - C2*(77 + 9*sqrt(77))/154)*exp(t**3*(sqrt(77) + 9)/6 + 5*t**2/2))]
    assert dsolve(eqs10) == sol10
    assert checksysodesol(eqs10 , sol10) == (True , [0,0])

    eqs11 = [Eq(diff(f(t), t), 5*t*f(t) + t**2*g(t)),
             Eq(diff(g(t), t), (1-t**2)*f(t) + (5*t + 9*t**2)*g(t))]
    sol11 = [Eq(f(t), C1*x0(t) + C2*x0(t)*Integral(t**2*exp(Integral(5*t, t))*exp(Integral(9*t**2 + 5*t, t))/x0(t)**2, t)),
             Eq(g(t), C1*y0(t) + C2*(y0(t)*Integral(t**2*exp(Integral(5*t, t))*exp(Integral(9*t**2 + 5*t, t))/x0(t)**2, t) + exp(Integral(5*t, t))*exp(Integral(9*t**2 + 5*t, t))/x0(t)))]
    assert dsolve(eqs11) == sol11

@slow
def test_sysode_linear_neq_order1_type4():

    f, g, h, k = symbols('f g h k', cls=Function)
    x, t, a = symbols('x t a')
    r = symbols('r', real=True)

    eqs1 = [Eq(diff(f(r), r), f(r) + r*g(r) + r**2), Eq(diff(g(r), r), -r*f(r) + g(r) + r)]
    sol1 = [Eq(f(r), C1*exp(r)*sin(r**2/2) + C2*exp(r)*cos(r**2/2) + exp(r)*sin(r**2/2)*Integral(r**2*exp(-r)*sin(r**2/2) +
                r*exp(-r)*cos(r**2/2), r) + exp(r)*cos(r**2/2)*Integral(r**2*exp(-r)*cos(r**2/2) - r*exp(-r)*sin(r**2/2), r)),
            Eq(g(r), C1*exp(r)*cos(r**2/2) - C2*exp(r)*sin(r**2/2) - exp(r)*sin(r**2/2)*Integral(r**2*exp(-r)*cos(r**2/2) -
                r*exp(-r)*sin(r**2/2), r) + exp(r)*cos(r**2/2)*Integral(r**2*exp(-r)*sin(r**2/2) + r*exp(-r)*cos(r**2/2), r))]
    assert dsolve(eqs1) == sol1
    assert checksysodesol(eqs1, sol1) == (True, [0, 0])

    eqs2 = [Eq(diff(f(r), r), f(r) + r*g(r) + r), Eq(diff(g(r), r), -r*f(r) + g(r) + log(r))]
    sol2 = [Eq(f(r), C1*exp(r)*sin(r**2/2) + C2*exp(r)*cos(r**2/2) + exp(r)*sin(r**2/2)*Integral(r*exp(-r)*sin(r**2/2) +
                exp(-r)*log(r)*cos(r**2/2), r) + exp(r)*cos(r**2/2)*Integral(r*exp(-r)*cos(r**2/2) - exp(-r)*log(r)*sin(
                r**2/2), r)),
            Eq(g(r), C1*exp(r)*cos(r**2/2) - C2*exp(r)*sin(r**2/2) - exp(r)*sin(r**2/2)*Integral(r*exp(-r)*cos(r**2/2) -
                exp(-r)*log(r)*sin(r**2/2), r) + exp(r)*cos(r**2/2)*Integral(r*exp(-r)*sin(r**2/2) + exp(-r)*log(r)*cos(
                r**2/2), r))]
    # XXX: dsolve hangs for this in integration
    assert dsolve_system(eqs2, simplify=False, doit=False) == [sol2]
    assert checksysodesol(eqs2, sol2) == (True, [0, 0])

    eqs3 = [Eq(Derivative(f(x), x), x*(f(x) + g(x) + h(x)) + x),
            Eq(Derivative(g(x), x), x*(f(x) + g(x) + h(x)) + x),
            Eq(Derivative(h(x), x), x*(f(x) + g(x) + h(x)) + 1)]
    sol3 = [Eq(f(x), C1*Rational(-1, 3) + C2*Rational(-1, 3) + C3*Rational(2, 3) + x**2/6 + x*Rational(-1, 3) +
             (C1/3 + C2/3 + C3/3)*exp(x**2*Rational(3, 2)) +
             sqrt(6)*sqrt(pi)*erf(sqrt(6)*x/2)*exp(x**2*Rational(3, 2))/18 + Rational(-2, 9)),
            Eq(g(x), C1*Rational(2, 3) + C2*Rational(-1, 3) + C3*Rational(-1, 3) + x**2/6 + x*Rational(-1, 3) +
             (C1/3 + C2/3 + C3/3)*exp(x**2*Rational(3, 2)) +
             sqrt(6)*sqrt(pi)*erf(sqrt(6)*x/2)*exp(x**2*Rational(3, 2))/18 + Rational(-2, 9)),
            Eq(h(x), C1*Rational(-1, 3) + C2*Rational(2, 3) + C3*Rational(-1, 3) + x**2*Rational(-1, 3) +
             x*Rational(2, 3) + (C1/3 + C2/3 + C3/3)*exp(x**2*Rational(3, 2)) +
             sqrt(6)*sqrt(pi)*erf(sqrt(6)*x/2)*exp(x**2*Rational(3, 2))/18 + Rational(-2, 9))]
    assert dsolve(eqs3) == sol3
    assert checksysodesol(eqs3, sol3) == (True, [0, 0, 0])

    eqs4 = [Eq(Derivative(f(x), x), x*(f(x) + g(x) + h(x)) + sin(x)),
            Eq(Derivative(g(x), x), x*(f(x) + g(x) + h(x)) + sin(x)),
            Eq(Derivative(h(x), x), x*(f(x) + g(x) + h(x)) + sin(x))]
    sol4 = [
        Eq(
            f(x),
            -C1*Rational(1, 3)
            - C2*Rational(1, 3)
            + 2*C3*Rational(1, 3)
            + (C1*Rational(1, 3) + C2*Rational(1, 3) + C3*Rational(1, 3))
              * exp(3*x**2/2)
            - sqrt(6)*I*sqrt(pi)*exp(-Rational(1, 6))*exp(3*x**2/2)
              * erf(sqrt(6)*x/2 - sqrt(6)*I/6)
              * Rational(1, 12)
            + sqrt(6)*I*sqrt(pi)*exp(-Rational(1, 6))*exp(3*x**2/2)
              * erf(sqrt(6)*x/2 + sqrt(6)*I/6)
              * Rational(1, 12)
        ),
        Eq(
            g(x),
            2*C1*Rational(1, 3)
            - C2*Rational(1, 3)
            - C3*Rational(1, 3)
            + (C1*Rational(1, 3) + C2*Rational(1, 3) + C3*Rational(1, 3))
              * exp(3*x**2/2)
            - sqrt(6)*I*sqrt(pi)*exp(-Rational(1, 6))*exp(3*x**2/2)
              * erf(sqrt(6)*x/2 - sqrt(6)*I/6)
              * Rational(1, 12)
            + sqrt(6)*I*sqrt(pi)*exp(-Rational(1, 6))*exp(3*x**2/2)
              * erf(sqrt(6)*x/2 + sqrt(6)*I/6)
              * Rational(1, 12)
        ),
        Eq(
            h(x),
            -C1*Rational(1, 3)
            + 2*C2*Rational(1, 3)
            - C3*Rational(1, 3)
            + (C1*Rational(1, 3) + C2*Rational(1, 3) + C3*Rational(1, 3))
              * exp(3*x**2/2)
            - sqrt(6)*I*sqrt(pi)*exp(-Rational(1, 6))*exp(3*x**2/2)
              * erf(sqrt(6)*x/2 - sqrt(6)*I/6)
              * Rational(1, 12)
            + sqrt(6)*I*sqrt(pi)*exp(-Rational(1, 6))*exp(3*x**2/2)
              * erf(sqrt(6)*x/2 + sqrt(6)*I/6)
              * Rational(1, 12)
        )
    ]
    assert dsolve(eqs4) == sol4
    assert checksysodesol(eqs4, sol4) == (True, [0, 0, 0])

    eqs5 = [Eq(Derivative(f(x), x), x*(f(x) + g(x) + h(x) + k(x) + 1)),
            Eq(Derivative(g(x), x), x*(f(x) + g(x) + h(x) + k(x) + 1)),
            Eq(Derivative(h(x), x), x*(f(x) + g(x) + h(x) + k(x) + 1)),
            Eq(Derivative(k(x), x), x*(f(x) + g(x) + h(x) + k(x) + 1))]
    sol5 = [Eq(f(x), C1*Rational(-1, 4) + C2*Rational(-1, 4) + C3*Rational(-1, 4) + C4*Rational(3, 4) + (C1/4 +
             C2/4 + C3/4 + C4/4)*exp(2*x**2) + Rational(-1, 4)),
            Eq(g(x), C1*Rational(3, 4) + C2*Rational(-1, 4) + C3*Rational(-1, 4) + C4*Rational(-1, 4) + (C1/4 +
             C2/4 + C3/4 + C4/4)*exp(2*x**2) + Rational(-1, 4)),
            Eq(h(x), C1*Rational(-1, 4) + C2*Rational(3, 4) + C3*Rational(-1, 4) + C4*Rational(-1, 4) + (C1/4 +
             C2/4 + C3/4 + C4/4)*exp(2*x**2) + Rational(-1, 4)),
            Eq(k(x), C1*Rational(-1, 4) + C2*Rational(-1, 4) + C3*Rational(3, 4) + C4*Rational(-1, 4) + (C1/4 +
             C2/4 + C3/4 + C4/4)*exp(2*x**2) + Rational(-1, 4))]
    assert dsolve(eqs5) == sol5
    assert checksysodesol(eqs5, sol5) == (True, [0, 0, 0, 0])

    eqs6 = [Eq(Derivative(f(x), x), x**2*(f(x) + g(x) + h(x) + k(x) + 1)),
            Eq(Derivative(g(x), x), x**2*(f(x) + g(x) + h(x) + k(x) + 1)),
            Eq(Derivative(h(x), x), x**2*(f(x) + g(x) + h(x) + k(x) + 1)),
            Eq(Derivative(k(x), x), x**2*(f(x) + g(x) + h(x) + k(x) + 1))]
    sol6 = [Eq(f(x), C1*Rational(-1, 4) + C2*Rational(-1, 4) + C3*Rational(-1, 4) + C4*Rational(3, 4) + (C1/4 +
             C2/4 + C3/4 + C4/4)*exp(x**3*Rational(4, 3)) + Rational(-1, 4)),
            Eq(g(x), C1*Rational(3, 4) + C2*Rational(-1, 4) + C3*Rational(-1, 4) + C4*Rational(-1, 4) + (C1/4 +
             C2/4 + C3/4 + C4/4)*exp(x**3*Rational(4, 3)) + Rational(-1, 4)),
            Eq(h(x), C1*Rational(-1, 4) + C2*Rational(3, 4) + C3*Rational(-1, 4) + C4*Rational(-1, 4) + (C1/4 +
             C2/4 + C3/4 + C4/4)*exp(x**3*Rational(4, 3)) + Rational(-1, 4)),
            Eq(k(x), C1*Rational(-1, 4) + C2*Rational(-1, 4) + C3*Rational(3, 4) + C4*Rational(-1, 4) + (C1/4 +
             C2/4 + C3/4 + C4/4)*exp(x**3*Rational(4, 3)) + Rational(-1, 4))]
    assert dsolve(eqs6) == sol6
    assert checksysodesol(eqs6, sol6) == (True, [0, 0, 0, 0])

    eqs7 = [Eq(Derivative(f(x), x), (f(x) + g(x) + h(x))*log(x) + sin(x)), Eq(Derivative(g(x), x), (f(x) + g(x)
            + h(x))*log(x) + sin(x)), Eq(Derivative(h(x), x), (f(x) + g(x) + h(x))*log(x) + sin(x))]
    sol7 = [Eq(f(x), -C1/3 - C2/3 + 2*C3/3 + (C1/3 + C2/3 +
                C3/3)*exp(x*(3*log(x) - 3)) + exp(x*(3*log(x) -
                    3))*Integral(exp(3*x)*exp(-3*x*log(x))*sin(x), x)),
            Eq(g(x), 2*C1/3 - C2/3 - C3/3 + (C1/3 + C2/3 +
                C3/3)*exp(x*(3*log(x) - 3)) + exp(x*(3*log(x) -
                    3))*Integral(exp(3*x)*exp(-3*x*log(x))*sin(x), x)),
            Eq(h(x), -C1/3 + 2*C2/3 - C3/3 + (C1/3 + C2/3 +
                C3/3)*exp(x*(3*log(x) - 3)) + exp(x*(3*log(x) -
                    3))*Integral(exp(3*x)*exp(-3*x*log(x))*sin(x), x))]
    with dotprodsimp(True):
        assert dsolve(eqs7, simplify=False, doit=False) == sol7
    assert checksysodesol(eqs7, sol7) == (True, [0, 0, 0])

    eqs8 = [Eq(Derivative(f(x), x), (f(x) + g(x) + h(x) + k(x))*log(x) + sin(x)), Eq(Derivative(g(x), x), (f(x)
            + g(x) + h(x) + k(x))*log(x) + sin(x)), Eq(Derivative(h(x), x), (f(x) + g(x) + h(x) + k(x))*log(x) +
            sin(x)), Eq(Derivative(k(x), x), (f(x) + g(x) + h(x) + k(x))*log(x) + sin(x))]
    sol8 = [Eq(f(x), -C1/4 - C2/4 - C3/4 + 3*C4/4 + (C1/4 + C2/4 + C3/4 +
                C4/4)*exp(x*(4*log(x) - 4)) + exp(x*(4*log(x) -
                    4))*Integral(exp(4*x)*exp(-4*x*log(x))*sin(x), x)),
            Eq(g(x), 3*C1/4 - C2/4 - C3/4 - C4/4 + (C1/4 + C2/4 + C3/4 +
                C4/4)*exp(x*(4*log(x) - 4)) + exp(x*(4*log(x) -
                    4))*Integral(exp(4*x)*exp(-4*x*log(x))*sin(x), x)),
            Eq(h(x), -C1/4 + 3*C2/4 - C3/4 - C4/4 + (C1/4 + C2/4 + C3/4 +
                C4/4)*exp(x*(4*log(x) - 4)) + exp(x*(4*log(x) -
                    4))*Integral(exp(4*x)*exp(-4*x*log(x))*sin(x), x)),
            Eq(k(x), -C1/4 - C2/4 + 3*C3/4 - C4/4 + (C1/4 + C2/4 + C3/4 +
                C4/4)*exp(x*(4*log(x) - 4)) + exp(x*(4*log(x) -
                    4))*Integral(exp(4*x)*exp(-4*x*log(x))*sin(x), x))]
    with dotprodsimp(True):
        assert dsolve(eqs8) == sol8
    assert checksysodesol(eqs8, sol8) == (True, [0, 0, 0, 0])


def test_sysode_linear_neq_order1_type5_type6():
    f, g = symbols("f g", cls=Function)
    x, x_ = symbols("x x_")

    # Type 5
    eqs1 = [Eq(Derivative(f(x), x), (2*f(x) + g(x))/x), Eq(Derivative(g(x), x), (f(x) + 2*g(x))/x)]
    sol1 = [Eq(f(x), -C1*x + C2*x**3), Eq(g(x), C1*x + C2*x**3)]
    assert dsolve(eqs1) == sol1
    assert checksysodesol(eqs1, sol1) == (True, [0, 0])

    # Type 6
    eqs2 = [Eq(Derivative(f(x), x), (2*f(x) + g(x) + 1)/x),
            Eq(Derivative(g(x), x), (x + f(x) + 2*g(x))/x)]
    sol2 = [Eq(f(x), C2*x**3 - x*(C1 + Rational(1, 4)) + x*log(x)*Rational(-1, 2) + Rational(-2, 3)),
            Eq(g(x), C2*x**3 + x*log(x)/2 + x*(C1 + Rational(-1, 4)) + Rational(1, 3))]
    assert dsolve(eqs2) == sol2
    assert checksysodesol(eqs2, sol2) == (True, [0, 0])


def test_higher_order_to_first_order():
    f, g = symbols('f g', cls=Function)
    x = symbols('x')

    eqs1 = [Eq(Derivative(f(x), (x, 2)), 2*f(x) + g(x)),
            Eq(Derivative(g(x), (x, 2)), -f(x))]
    sol1 = [Eq(f(x), -C2*x*exp(-x) + C3*x*exp(x) - (C1 - C2)*exp(-x) + (C3 + C4)*exp(x)),
            Eq(g(x), C2*x*exp(-x) - C3*x*exp(x) + (C1 + C2)*exp(-x) + (C3 - C4)*exp(x))]
    assert dsolve(eqs1) == sol1
    assert checksysodesol(eqs1, sol1) == (True, [0, 0])

    eqs2 = [Eq(f(x).diff(x, 2), 0), Eq(g(x).diff(x, 2), f(x))]
    sol2 = [Eq(f(x), C1 + C2*x), Eq(g(x), C1*x**2/2 + C2*x**3/6 + C3 + C4*x)]
    assert dsolve(eqs2) == sol2
    assert checksysodesol(eqs2, sol2) == (True, [0, 0])

    eqs3 = [Eq(Derivative(f(x), (x, 2)), 2*f(x)),
            Eq(Derivative(g(x), (x, 2)), -f(x) + 2*g(x))]
    sol3 = [Eq(f(x), -8*sqrt(2)*C1*exp(-sqrt(2)*x) + 8*sqrt(2)*C2*exp(sqrt(2)*x)),
            Eq(g(x), -4*C1*x*exp(-sqrt(2)*x) - 4*C2*x*exp(sqrt(2)*x)
               - (2*sqrt(2)*C1 + 4*C3)*exp(-sqrt(2)*x) + (2*sqrt(2)*C2 - 4*C4)*exp(sqrt(2)*x))]
    assert dsolve(eqs3) == sol3
    assert checksysodesol(eqs3, sol3) == (True, [0, 0])

    eqs4 = [Eq(Derivative(f(x), (x, 2)), 2*f(x) + g(x)),
            Eq(Derivative(g(x), (x, 2)), 2*g(x))]
    sol4 = [Eq(f(x), sqrt(2)*C1*x*exp(sqrt(2)*x) - sqrt(2)*C3*x*exp(-sqrt(2)*x)
               - (C1 - sqrt(2)*C2)*exp(sqrt(2)*x) - (C3 + sqrt(2)*C4)*exp(-sqrt(2)*x)),
            Eq(g(x), 4*C1*exp(sqrt(2)*x) + 4*C3*exp(-sqrt(2)*x))]
    assert dsolve(eqs4) == sol4
    assert checksysodesol(eqs4, sol4) == (True, [0, 0])

    eqs5 = [Eq(f(x).diff(x, 2), f(x)), Eq(g(x).diff(x, 2), f(x))]
    sol5 = [Eq(f(x), -C1*exp(-x) + C2*exp(x)), Eq(g(x), -C1*exp(-x) + C2*exp(x) + C3 + C4*x)]
    assert dsolve(eqs5) == sol5
    assert checksysodesol(eqs5, sol5) == (True, [0, 0])

    eqs6 = [Eq(Derivative(f(x), (x, 2)), f(x) + g(x)),
            Eq(Derivative(g(x), (x, 2)), -f(x) - g(x))]
    sol6 = [Eq(f(x), C1 + C2*x**2/2 + C2 + C4*x**3/6 + x*(C3 + C4)),
            Eq(g(x), -C1 + C2*x**2*Rational(-1, 2) - C3*x + C4*x**3*Rational(-1, 6))]
    assert dsolve(eqs6) == sol6
    assert checksysodesol(eqs6, sol6) == (True, [0, 0])

    eqs7 = [Eq(Derivative(f(x), (x, 2)), f(x) + g(x) + 1),
            Eq(Derivative(g(x), (x, 2)), f(x) + g(x) + 1)]
    sol7 = [Eq(f(x), -C1 - C2*x + sqrt(2)*C3*exp(sqrt(2)*x) - sqrt(2)*C4*exp(-sqrt(2)*x) - Rational(1,2)),
            Eq(g(x), C1 + C2*x + sqrt(2)*C3*exp(sqrt(2)*x) - sqrt(2)*C4*exp(-sqrt(2)*x) - Rational(1,2))]
    assert dsolve(eqs7) == sol7
    assert checksysodesol(eqs7, sol7) == (True, [0, 0])

    eqs8 = [Eq(Derivative(f(x), (x, 2)), f(x) + g(x) + 1),
            Eq(Derivative(g(x), (x, 2)), -f(x) - g(x) + 1)]
    sol8 = [Eq(f(x), C1 + C2 + C4*x**3/6 + x**4/12 + x**2*(C2/2 + Rational(1, 2)) + x*(C3 + C4)),
            Eq(g(x), -C1 - C3*x + C4*x**3*Rational(-1, 6) + x**4*Rational(-1, 12) - x**2*(C2/2 + Rational(-1,
             2)))]
    assert dsolve(eqs8) == sol8
    assert checksysodesol(eqs8, sol8) == (True, [0, 0])

    x, y = symbols('x, y', cls=Function)
    t, l = symbols('t, l')

    eqs10 = [Eq(Derivative(x(t), (t, 2)), 5*x(t) + 43*y(t)),
             Eq(Derivative(y(t), (t, 2)), x(t) + 9*y(t))]
    sol10 = [Eq(x(t), -43*C1*sqrt(7 - sqrt(47))*exp(-t*sqrt(7 - sqrt(47)))
                + 43*C2*sqrt(7 - sqrt(47))*exp(t*sqrt(7 - sqrt(47)))
                - 43*C3*sqrt(sqrt(47) + 7)*exp(-t*sqrt(sqrt(47) + 7))
                + 43*C4*sqrt(sqrt(47) + 7)*exp(t*sqrt(sqrt(47) + 7))),
             Eq(y(t), -C1*(2 - sqrt(47))*sqrt(7 - sqrt(47))*exp(-t*sqrt(7 - sqrt(47)))
                + C2*(2 - sqrt(47))*sqrt(7 - sqrt(47))*exp(t*sqrt(7 - sqrt(47)))
                - C3*(2 + sqrt(47))*sqrt(sqrt(47) + 7)*exp(-t*sqrt(sqrt(47) + 7))
                + C4*(2 + sqrt(47))*sqrt(sqrt(47) + 7)*exp(t*sqrt(sqrt(47) + 7)))]
    assert dsolve(eqs10) == sol10
    assert checksysodesol(eqs10, sol10) == (True, [0, 0])

    eqs11 = [Eq(7*x(t) + Derivative(x(t), (t, 2)) - 9*Derivative(y(t), t), 0),
             Eq(7*y(t) + 9*Derivative(x(t), t) + Derivative(y(t), (t, 2)), 0)]
    sol11 = [Eq(y(t), 63*C1*sin(sqrt(2)*t*sqrt(95 - 9*sqrt(109))/2)
                + 63*C2*sin(sqrt(2)*t*sqrt(9*sqrt(109)+ 95)/2)
                - 63*C3*cos(sqrt(2)*t*sqrt(95 - 9*sqrt(109))/2)
                - 63*C4*cos(sqrt(2)*t*sqrt(9*sqrt(109) + 95)/2)),
             Eq(x(t), 9*C1*sqrt(95 - 9*sqrt(109))*(9*sqrt(2) + sqrt(218))
                *cos(sqrt(2)*t*sqrt(95 - 9*sqrt(109))/2)/4 + 9*C2*sqrt(9*sqrt(109) + 95)
                *(-sqrt(218) + 9*sqrt(2))*cos(sqrt(2)*t*sqrt(9*sqrt(109) + 95)/2)/4
                + 9*C3*sqrt(95 - 9*sqrt(109))*(9*sqrt(2) + sqrt(218))*sin(sqrt(2)
                *t*sqrt(95 - 9*sqrt(109))/2)/4 + 9*C4*sqrt(9*sqrt(109) + 95)
                *(-sqrt(218) + 9*sqrt(2))*sin(sqrt(2)*t*sqrt(9*sqrt(109) + 95)/2)/4)]
    assert dsolve(eqs11) == sol11
    assert checksysodesol(eqs11, sol11) == (True, [0, 0])

    # Euler Systems
    # Note: To add examples of euler systems solver with non-homogeneous term.
    eqs13 = [Eq(Derivative(f(t), (t, 2)), Derivative(f(t), t)/t + f(t)/t**2 + g(t)/t**2),
             Eq(Derivative(g(t), (t, 2)), g(t)/t**2)]
    sol13 = [Eq(f(t), -C1*t**(Rational(1,2) - sqrt(5)/2)
                - C2*t**(Rational(1,2) + sqrt(5)/2) + C3*t**(1 - sqrt(2)) + C4*t**(1 + sqrt(2))),
             Eq(g(t), C1*t**(Rational(1,2) - sqrt(5)/2)*(Rational(1,2) - sqrt(5)/2)
                + C2*t**(Rational(1,2) + sqrt(5)/2)*(Rational(1,2) + sqrt(5)/2))]
    assert checksysodesol(eqs13, sol13) == (True, [0, 0])

    # Solving systems using dsolve separately
    eqs14 = [Eq(Derivative(f(t), (t, 2)), t*f(t)),
         Eq(Derivative(g(t), (t, 2)), t*g(t))]
    sol14 = [Eq(f(t), C1*airyai(t) + C2*airybi(t)),
         Eq(g(t), C3*airyai(t) + C4*airybi(t))]
    assert dsolve(eqs14) == sol14
    assert checksysodesol(eqs14, sol14) == (True, [0, 0])


    eqs15 = [Eq(Derivative(x(t), (t, 2)), t*(4*Derivative(x(t), t) + 8*Derivative(y(t), t))),
             Eq(Derivative(y(t), (t, 2)), t*(12*Derivative(x(t), t) - 6*Derivative(y(t), t)))]
    sol15 = [Eq(x(t), C1 - erf(sqrt(6)*t)*(sqrt(6)*sqrt(pi)*C2/33 + sqrt(6)*sqrt(pi)*C3*Rational(-1, 44)) +
              erfi(sqrt(5)*t)*(sqrt(5)*sqrt(pi)*C2*Rational(2, 55) + sqrt(5)*sqrt(pi)*C3*Rational(4, 55))),
             Eq(y(t), C4 + erf(sqrt(6)*t)*(sqrt(6)*sqrt(pi)*C2*Rational(2, 33) + sqrt(6)*sqrt(pi)*C3*Rational(-1,
              22)) + erfi(sqrt(5)*t)*(sqrt(5)*sqrt(pi)*C2*Rational(3, 110) + sqrt(5)*sqrt(pi)*C3*Rational(3, 55)))]
    assert dsolve(eqs15) == sol15
    assert checksysodesol(eqs15, sol15) == (True, [0, 0])


@slow
def test_higher_order_to_first_order_9():
    f, g = symbols('f g', cls=Function)
    x = symbols('x')

    eqs9 = [f(x) + g(x) - 2*exp(I*x) + 2*Derivative(f(x), x) + Derivative(f(x), (x, 2)),
            f(x) + g(x) - 2*exp(I*x) + 2*Derivative(g(x), x) + Derivative(g(x), (x, 2))]
    sol9 =  [Eq(f(x), -2*C1 + C4*exp(-2*x) - (C2 - C3)*exp(-x)*cos(x)
                + (C2 + C3)*exp(-x)*sin(x) + Mul(2, (1 - 2*I), evaluate=False)*exp(I*x)
                *sin(x)**2/5 + Mul(2, (1 - 2*I), evaluate=False)*exp(I*x)*cos(x)**2/5),
             Eq(g(x), 2*C1 - C4*exp(-2*x) - (C2 - C3)*exp(-x)*cos(x) + (C2 + C3)*exp(-x)*sin(x)
                + Mul(2, (1 - 2*I), evaluate=False)*exp(I*x)*sin(x)**2/5 + Mul(2, (1 - 2*I), evaluate=False)
                *exp(I*x)*cos(x)**2/5)]
    assert dsolve(eqs9) == sol9
    assert checksysodesol(eqs9, sol9) == (True, [0, 0])


def test_higher_order_to_first_order_12():
    f, g = symbols('f g', cls=Function)
    x = symbols('x')

    x, y = symbols('x, y', cls=Function)
    t, l = symbols('t, l')

    eqs12 = [Eq(4*x(t) + Derivative(x(t), (t, 2)) + 8*Derivative(y(t), t), 0),
             Eq(4*y(t) - 8*Derivative(x(t), t) + Derivative(y(t), (t, 2)), 0)]
    sol12 = [Eq(y(t), -32*C1*sin(2*t*sqrt(9 - 4*sqrt(5))) - 32*C2*sin(2*t*sqrt(4*sqrt(5) + 9))
                + 32*C3*cos(2*t*sqrt(9 - 4*sqrt(5))) + 32*C4*cos(2*t*sqrt(4*sqrt(5) + 9))),
             Eq(x(t), 32*C1*(2 + sqrt(5))*sqrt(9 - 4*sqrt(5))*cos(2*t*sqrt(9 - 4*sqrt(5)))
                + 32*C2*(2 - sqrt(5))*sqrt(4*sqrt(5) + 9)*cos(2*t*sqrt(4*sqrt(5) + 9))
                + 32*C3*(2 + sqrt(5))*sqrt(9 - 4*sqrt(5))*sin(2*t*sqrt(9 - 4*sqrt(5)))
                + 32*C4*(2 - sqrt(5))*sqrt(4*sqrt(5) + 9)*sin(2*t*sqrt(4*sqrt(5) + 9)))]
    assert dsolve(eqs12) == sol12
    assert checksysodesol(eqs12, sol12) == (True, [0, 0])


def test_second_order_to_first_order_2():
    f, g = symbols("f g", cls=Function)
    x, t, x_, t_, d, a, m = symbols("x t x_ t_ d a m")

    eqs2 = [Eq(f(x).diff(x, 2), 2*(x*g(x).diff(x) - g(x))),
            Eq(g(x).diff(x, 2),-2*(x*f(x).diff(x) - f(x)))]
    sol2 = [Eq(f(x), C1*x + x*Integral(C2*exp(-x_)*exp(I*exp(2*x_))/2 + C2*exp(-x_)*exp(-I*exp(2*x_))/2 -
                I*C3*exp(-x_)*exp(I*exp(2*x_))/2 + I*C3*exp(-x_)*exp(-I*exp(2*x_))/2, (x_, log(x)))),
            Eq(g(x), C4*x + x*Integral(I*C2*exp(-x_)*exp(I*exp(2*x_))/2 - I*C2*exp(-x_)*exp(-I*exp(2*x_))/2 +
                C3*exp(-x_)*exp(I*exp(2*x_))/2 + C3*exp(-x_)*exp(-I*exp(2*x_))/2, (x_, log(x))))]
    # XXX: dsolve hangs for this in integration
    assert dsolve_system(eqs2, simplify=False, doit=False) == [sol2]
    assert checksysodesol(eqs2, sol2) == (True, [0, 0])

    eqs3 = (Eq(diff(f(t),t,t), 9*t*diff(g(t),t)-9*g(t)), Eq(diff(g(t),t,t),7*t*diff(f(t),t)-7*f(t)))
    sol3 = [Eq(f(t), C1*t + t*Integral(C2*exp(-t_)*exp(3*sqrt(7)*exp(2*t_)/2)/2 + C2*exp(-t_)*
                exp(-3*sqrt(7)*exp(2*t_)/2)/2 + 3*sqrt(7)*C3*exp(-t_)*exp(3*sqrt(7)*exp(2*t_)/2)/14 -
                3*sqrt(7)*C3*exp(-t_)*exp(-3*sqrt(7)*exp(2*t_)/2)/14, (t_, log(t)))),
            Eq(g(t), C4*t + t*Integral(sqrt(7)*C2*exp(-t_)*exp(3*sqrt(7)*exp(2*t_)/2)/6 - sqrt(7)*C2*exp(-t_)*
                exp(-3*sqrt(7)*exp(2*t_)/2)/6 + C3*exp(-t_)*exp(3*sqrt(7)*exp(2*t_)/2)/2 + C3*exp(-t_)*exp(-3*sqrt(7)*
                exp(2*t_)/2)/2, (t_, log(t))))]
    # XXX: dsolve hangs for this in integration
    assert dsolve_system(eqs3, simplify=False, doit=False) == [sol3]
    assert checksysodesol(eqs3, sol3) == (True, [0, 0])

    # Regression Test case for sympy#19238
    # https://github.com/sympy/sympy/issues/19238
    # Note: When the doit method is removed, these particular types of systems
    # can be divided first so that we have lesser number of big matrices.
    eqs5 = [Eq(Derivative(g(t), (t, 2)), a*m),
            Eq(Derivative(f(t), (t, 2)), 0)]
    sol5 = [Eq(g(t), C1 + C2*t + a*m*t**2/2),
            Eq(f(t), C3 + C4*t)]
    assert dsolve(eqs5) == sol5
    assert checksysodesol(eqs5, sol5) == (True, [0, 0])

    # Type 2
    eqs6 = [Eq(Derivative(f(t), (t, 2)), f(t)/t**4),
            Eq(Derivative(g(t), (t, 2)), d*g(t)/t**4)]
    sol6 = [Eq(f(t), C1*sqrt(t**2)*exp(-1/t) - C2*sqrt(t**2)*exp(1/t)),
            Eq(g(t), C3*sqrt(t**2)*exp(-sqrt(d)/t)*d**Rational(-1, 2) -
             C4*sqrt(t**2)*exp(sqrt(d)/t)*d**Rational(-1, 2))]
    assert dsolve(eqs6) == sol6
    assert checksysodesol(eqs6, sol6) == (True, [0, 0])


@slow
def test_second_order_to_first_order_slow1():
    f, g = symbols("f g", cls=Function)
    x, t, x_, t_, d, a, m = symbols("x t x_ t_ d a m")

    # Type 1

    eqs1 = [Eq(f(x).diff(x, 2), 2/x *(x*g(x).diff(x) - g(x))),
           Eq(g(x).diff(x, 2),-2/x *(x*f(x).diff(x) - f(x)))]
    sol1 = [Eq(f(x), C1*x - 4*C2*x*Ci(2*x) + 2*C2*sin(2*x) - 4*C3*x*Si(2*x) - 2*C3*cos(2*x)),
            Eq(g(x), 4*C2*x*Si(2*x) + 2*C2*cos(2*x) - 4*C3*x*Ci(2*x) + 2*C3*sin(2*x) + C4*x)]
    assert dsolve(eqs1) == sol1
    assert checksysodesol(eqs1, sol1) == (True, [0, 0])


def test_second_order_to_first_order_slow4():
    f, g = symbols("f g", cls=Function)
    x, t, x_, t_, d, a, m = symbols("x t x_ t_ d a m")

    eqs4 = [Eq(Derivative(f(t), (t, 2)), t*sin(t)*Derivative(g(t), t) - g(t)*sin(t)),
            Eq(Derivative(g(t), (t, 2)), t*sin(t)*Derivative(f(t), t) - f(t)*sin(t))]
    sol4 = [Eq(f(t), C1*t + t*Integral(C2*exp(-t_)*exp(exp(t_)*cos(exp(t_)))*exp(-sin(exp(t_)))/2 +
                C2*exp(-t_)*exp(-exp(t_)*cos(exp(t_)))*exp(sin(exp(t_)))/2 - C3*exp(-t_)*exp(exp(t_)*cos(exp(t_)))*
                exp(-sin(exp(t_)))/2 +
                C3*exp(-t_)*exp(-exp(t_)*cos(exp(t_)))*exp(sin(exp(t_)))/2, (t_, log(t)))),
            Eq(g(t), C4*t + t*Integral(-C2*exp(-t_)*exp(exp(t_)*cos(exp(t_)))*exp(-sin(exp(t_)))/2 +
                C2*exp(-t_)*exp(-exp(t_)*cos(exp(t_)))*exp(sin(exp(t_)))/2 + C3*exp(-t_)*exp(exp(t_)*cos(exp(t_)))*
                exp(-sin(exp(t_)))/2 + C3*exp(-t_)*exp(-exp(t_)*cos(exp(t_)))*exp(sin(exp(t_)))/2, (t_, log(t))))]
    # XXX: dsolve hangs for this in integration
    assert dsolve_system(eqs4, simplify=False, doit=False) == [sol4]
    assert checksysodesol(eqs4, sol4) == (True, [0, 0])


def test_component_division():
    f, g, h, k = symbols('f g h k', cls=Function)
    x = symbols("x")
    funcs = [f(x), g(x), h(x), k(x)]

    eqs1 = [Eq(Derivative(f(x), x), 2*f(x)),
            Eq(Derivative(g(x), x), f(x)),
            Eq(Derivative(h(x), x), h(x)),
            Eq(Derivative(k(x), x), h(x)**4 + k(x))]
    sol1 = [Eq(f(x), 2*C1*exp(2*x)),
            Eq(g(x), C1*exp(2*x) + 2*C2),
            Eq(h(x), C3*exp(x)),
            Eq(k(x), C3**4*exp(4*x)/3 + C4*exp(x))]
    assert dsolve(eqs1) == sol1
    assert checksysodesol(eqs1, sol1) == (True, [0, 0, 0, 0])

    components1 = {((Eq(Derivative(f(x), x), 2*f(x)),), (Eq(Derivative(g(x), x), f(x)),)),
                   ((Eq(Derivative(h(x), x), h(x)),), (Eq(Derivative(k(x), x), h(x)**4 + k(x)),))}
    eqsdict1 = ({f(x): set(), g(x): {f(x)}, h(x): set(), k(x): {h(x)}},
                {f(x): Eq(Derivative(f(x), x), 2*f(x)),
                g(x): Eq(Derivative(g(x), x), f(x)),
                h(x): Eq(Derivative(h(x), x), h(x)),
                k(x): Eq(Derivative(k(x), x), h(x)**4 + k(x))})
    graph1 = [{f(x), g(x), h(x), k(x)}, {(g(x), f(x)), (k(x), h(x))}]
    assert {tuple(tuple(scc) for scc in wcc) for wcc in _component_division(eqs1, funcs, x)} == components1
    assert _eqs2dict(eqs1, funcs) == eqsdict1
    assert [set(element) for element in _dict2graph(eqsdict1[0])] == graph1

    eqs2 = [Eq(Derivative(f(x), x), 2*f(x)),
            Eq(Derivative(g(x), x), f(x)),
            Eq(Derivative(h(x), x), h(x)),
            Eq(Derivative(k(x), x), f(x)**4 + k(x))]
    sol2 = [Eq(f(x), C1*exp(2*x)),
            Eq(g(x), C1*exp(2*x)/2 + C2),
            Eq(h(x), C3*exp(x)),
            Eq(k(x), C1**4*exp(8*x)/7 + C4*exp(x))]
    assert dsolve(eqs2) == sol2
    assert checksysodesol(eqs2, sol2) == (True, [0, 0, 0, 0])

    components2 = {frozenset([(Eq(Derivative(f(x), x), 2*f(x)),),
                    (Eq(Derivative(g(x), x), f(x)),),
                    (Eq(Derivative(k(x), x), f(x)**4 + k(x)),)]),
                   frozenset([(Eq(Derivative(h(x), x), h(x)),)])}
    eqsdict2 = ({f(x): set(), g(x): {f(x)}, h(x): set(), k(x): {f(x)}},
                 {f(x): Eq(Derivative(f(x), x), 2*f(x)),
                  g(x): Eq(Derivative(g(x), x), f(x)),
                  h(x): Eq(Derivative(h(x), x), h(x)),
                  k(x): Eq(Derivative(k(x), x), f(x)**4 + k(x))})
    graph2 = [{f(x), g(x), h(x), k(x)}, {(g(x), f(x)), (k(x), f(x))}]
    assert {frozenset(tuple(scc) for scc in wcc) for wcc in _component_division(eqs2, funcs, x)} == components2
    assert _eqs2dict(eqs2, funcs) == eqsdict2
    assert [set(element) for element in _dict2graph(eqsdict2[0])] == graph2

    eqs3 = [Eq(Derivative(f(x), x), 2*f(x)),
            Eq(Derivative(g(x), x), x + f(x)),
            Eq(Derivative(h(x), x), h(x)),
            Eq(Derivative(k(x), x), f(x)**4 + k(x))]
    sol3 = [Eq(f(x), C1*exp(2*x)),
            Eq(g(x), C1*exp(2*x)/2 + C2 + x**2/2),
            Eq(h(x), C3*exp(x)),
            Eq(k(x), C1**4*exp(8*x)/7 + C4*exp(x))]
    assert dsolve(eqs3) == sol3
    assert checksysodesol(eqs3, sol3) == (True, [0, 0, 0, 0])

    components3 = {frozenset([(Eq(Derivative(f(x), x), 2*f(x)),),
                    (Eq(Derivative(g(x), x), x + f(x)),),
                    (Eq(Derivative(k(x), x), f(x)**4 + k(x)),)]),
                    frozenset([(Eq(Derivative(h(x), x), h(x)),),])}
    eqsdict3 = ({f(x): set(), g(x): {f(x)}, h(x): set(), k(x): {f(x)}},
                {f(x): Eq(Derivative(f(x), x), 2*f(x)),
                g(x): Eq(Derivative(g(x), x), x + f(x)),
                h(x): Eq(Derivative(h(x), x), h(x)),
                k(x): Eq(Derivative(k(x), x), f(x)**4 + k(x))})
    graph3 = [{f(x), g(x), h(x), k(x)}, {(g(x), f(x)), (k(x), f(x))}]
    assert {frozenset(tuple(scc) for scc in wcc) for wcc in _component_division(eqs3, funcs, x)} == components3
    assert _eqs2dict(eqs3, funcs) == eqsdict3
    assert [set(l) for l in _dict2graph(eqsdict3[0])] == graph3

    # Note: To be uncommented when the default option to call dsolve first for
    # single ODE system can be rearranged. This can be done after the doit
    # option in dsolve is made False by default.

    eqs4 = [Eq(Derivative(f(x), x), x*f(x) + 2*g(x)),
            Eq(Derivative(g(x), x), f(x) + x*g(x) + x),
            Eq(Derivative(h(x), x), h(x)),
            Eq(Derivative(k(x), x), f(x)**4 + k(x))]
    sol4 = [Eq(f(x), (C1/2 - sqrt(2)*C2/2 - sqrt(2)*Integral(x*exp(-x**2/2 - sqrt(2)*x)/2 + x*exp(-x**2/2 +\
                sqrt(2)*x)/2, x)/2 + Integral(sqrt(2)*x*exp(-x**2/2 - sqrt(2)*x)/2 - sqrt(2)*x*exp(-x**2/2 +\
                sqrt(2)*x)/2, x)/2)*exp(x**2/2 - sqrt(2)*x) + (C1/2 + sqrt(2)*C2/2 + sqrt(2)*Integral(x*exp(-x**2/2
                - sqrt(2)*x)/2 + x*exp(-x**2/2 + sqrt(2)*x)/2, x)/2 + Integral(sqrt(2)*x*exp(-x**2/2 - sqrt(2)*x)/2
                - sqrt(2)*x*exp(-x**2/2 + sqrt(2)*x)/2, x)/2)*exp(x**2/2 + sqrt(2)*x)),
            Eq(g(x), (-sqrt(2)*C1/4 + C2/2 + Integral(x*exp(-x**2/2 - sqrt(2)*x)/2 + x*exp(-x**2/2 + sqrt(2)*x)/2, x)/2 -\
                sqrt(2)*Integral(sqrt(2)*x*exp(-x**2/2 - sqrt(2)*x)/2 - sqrt(2)*x*exp(-x**2/2 + sqrt(2)*x)/2,
                x)/4)*exp(x**2/2 - sqrt(2)*x) + (sqrt(2)*C1/4 + C2/2 + Integral(x*exp(-x**2/2 - sqrt(2)*x)/2 +
                x*exp(-x**2/2 + sqrt(2)*x)/2, x)/2 + sqrt(2)*Integral(sqrt(2)*x*exp(-x**2/2 - sqrt(2)*x)/2 -
                sqrt(2)*x*exp(-x**2/2 + sqrt(2)*x)/2, x)/4)*exp(x**2/2 + sqrt(2)*x)),
            Eq(h(x), C3*exp(x)),
            Eq(k(x), C4*exp(x) + exp(x)*Integral((C1*exp(x**2/2 - sqrt(2)*x)/2 + C1*exp(x**2/2 + sqrt(2)*x)/2 -
                sqrt(2)*C2*exp(x**2/2 - sqrt(2)*x)/2 + sqrt(2)*C2*exp(x**2/2 + sqrt(2)*x)/2 - sqrt(2)*exp(x**2/2 -
                sqrt(2)*x)*Integral(x*exp(-x**2/2 - sqrt(2)*x)/2 + x*exp(-x**2/2 + sqrt(2)*x)/2, x)/2 + exp(x**2/2 -
                sqrt(2)*x)*Integral(sqrt(2)*x*exp(-x**2/2 - sqrt(2)*x)/2 - sqrt(2)*x*exp(-x**2/2 + sqrt(2)*x)/2,
                x)/2 + sqrt(2)*exp(x**2/2 + sqrt(2)*x)*Integral(x*exp(-x**2/2 - sqrt(2)*x)/2 + x*exp(-x**2/2 +
                sqrt(2)*x)/2, x)/2 + exp(x**2/2 + sqrt(2)*x)*Integral(sqrt(2)*x*exp(-x**2/2 - sqrt(2)*x)/2 -
                sqrt(2)*x*exp(-x**2/2 + sqrt(2)*x)/2, x)/2)**4*exp(-x), x))]
    components4 = {(frozenset([Eq(Derivative(f(x), x), x*f(x) + 2*g(x)),
                    Eq(Derivative(g(x), x), x*g(x) + x + f(x))]),
                    frozenset([Eq(Derivative(k(x), x), f(x)**4 + k(x)),])),
                    (frozenset([Eq(Derivative(h(x), x), h(x)),]),)}
    eqsdict4 = ({f(x): {g(x)}, g(x): {f(x)}, h(x): set(), k(x): {f(x)}},
                {f(x): Eq(Derivative(f(x), x), x*f(x) + 2*g(x)),
                g(x): Eq(Derivative(g(x), x), x*g(x) + x + f(x)),
                h(x): Eq(Derivative(h(x), x), h(x)),
                k(x): Eq(Derivative(k(x), x), f(x)**4 + k(x))})
    graph4 = [{f(x), g(x), h(x), k(x)}, {(f(x), g(x)), (g(x), f(x)), (k(x), f(x))}]
    assert {tuple(frozenset(scc) for scc in wcc) for wcc in _component_division(eqs4, funcs, x)} == components4
    assert _eqs2dict(eqs4, funcs) == eqsdict4
    assert [set(element) for element in _dict2graph(eqsdict4[0])] == graph4
    # XXX: dsolve hangs in integration here:
    assert dsolve_system(eqs4, simplify=False, doit=False) == [sol4]
    assert checksysodesol(eqs4, sol4) == (True, [0, 0, 0, 0])

    eqs5 = [Eq(Derivative(f(x), x), x*f(x) + 2*g(x)),
            Eq(Derivative(g(x), x), x*g(x) + f(x)),
            Eq(Derivative(h(x), x), h(x)),
            Eq(Derivative(k(x), x), f(x)**4 + k(x))]
    sol5 = [Eq(f(x), (C1/2 - sqrt(2)*C2/2)*exp(x**2/2 - sqrt(2)*x) + (C1/2 + sqrt(2)*C2/2)*exp(x**2/2 + sqrt(2)*x)),
            Eq(g(x), (-sqrt(2)*C1/4 + C2/2)*exp(x**2/2 - sqrt(2)*x) + (sqrt(2)*C1/4 + C2/2)*exp(x**2/2 + sqrt(2)*x)),
            Eq(h(x), C3*exp(x)),
            Eq(k(x), C4*exp(x) + exp(x)*Integral((C1*exp(x**2/2 - sqrt(2)*x)/2 + C1*exp(x**2/2 + sqrt(2)*x)/2 -
                sqrt(2)*C2*exp(x**2/2 - sqrt(2)*x)/2 + sqrt(2)*C2*exp(x**2/2 + sqrt(2)*x)/2)**4*exp(-x), x))]
    components5 = {(frozenset([Eq(Derivative(f(x), x), x*f(x) + 2*g(x)),
                    Eq(Derivative(g(x), x), x*g(x) + f(x))]),
                    frozenset([Eq(Derivative(k(x), x), f(x)**4 + k(x)),])),
                    (frozenset([Eq(Derivative(h(x), x), h(x)),]),)}
    eqsdict5 = ({f(x): {g(x)}, g(x): {f(x)}, h(x): set(), k(x): {f(x)}},
                {f(x): Eq(Derivative(f(x), x), x*f(x) + 2*g(x)),
                g(x): Eq(Derivative(g(x), x), x*g(x) + f(x)),
                h(x): Eq(Derivative(h(x), x), h(x)),
                k(x): Eq(Derivative(k(x), x), f(x)**4 + k(x))})
    graph5 = [{f(x), g(x), h(x), k(x)}, {(f(x), g(x)), (g(x), f(x)), (k(x), f(x))}]
    assert {tuple(frozenset(scc) for scc in wcc) for wcc in _component_division(eqs5, funcs, x)} == components5
    assert _eqs2dict(eqs5, funcs) == eqsdict5
    assert [set(element) for element in _dict2graph(eqsdict5[0])] == graph5
    # XXX: dsolve hangs in integration here:
    assert dsolve_system(eqs5, simplify=False, doit=False) == [sol5]
    assert checksysodesol(eqs5, sol5) == (True, [0, 0, 0, 0])


def test_linodesolve():
    t, x, a = symbols("t x a")
    f, g, h = symbols("f g h", cls=Function)

    # Testing the Errors
    raises(ValueError, lambda: linodesolve(1, t))
    raises(ValueError, lambda: linodesolve(a, t))

    A1 = Matrix([[1, 2], [2, 4], [4, 6]])
    raises(NonSquareMatrixError, lambda: linodesolve(A1, t))

    A2 = Matrix([[1, 2, 1], [3, 1, 2]])
    raises(NonSquareMatrixError, lambda: linodesolve(A2, t))

    # Testing auto functionality
    func = [f(t), g(t)]
    eq = [Eq(f(t).diff(t) + g(t).diff(t), g(t)), Eq(g(t).diff(t), f(t))]
    ceq = canonical_odes(eq, func, t)
    (A1, A0), b = linear_ode_to_matrix(ceq[0], func, t, 1)
    A = A0
    sol = [C1*exp(t*(-Rational(1,2) + sqrt(5)/2)) + C2*exp(t*(-sqrt(5)/2 - Rational(1,2))),
           C1*(Rational(1,2) + sqrt(5)/2)*exp(t*(-Rational(1,2) + sqrt(5)/2))
           + C2*(Rational(1,2) - sqrt(5)/2)*exp(t*(-sqrt(5)/2 - Rational(1,2)))]
    assert constant_renumber(linodesolve(A, t), variables=Tuple(*eq).free_symbols) == sol

    # Testing the Errors
    raises(ValueError, lambda: linodesolve(1, t, b=Matrix([t+1])))
    raises(ValueError, lambda: linodesolve(a, t, b=Matrix([log(t) + sin(t)])))

    raises(ValueError, lambda: linodesolve(Matrix([7]), t, b=t**2))
    raises(ValueError, lambda: linodesolve(Matrix([a+10]), t, b=log(t)*cos(t)))

    raises(ValueError, lambda: linodesolve(7, t, b=t**2))
    raises(ValueError, lambda: linodesolve(a, t, b=log(t) + sin(t)))

    A1 = Matrix([[1, 2], [2, 4], [4, 6]])
    b1 = Matrix([t, 1, t**2])
    raises(NonSquareMatrixError, lambda: linodesolve(A1, t, b=b1))

    A2 = Matrix([[1, 2, 1], [3, 1, 2]])
    b2 = Matrix([t, t**2])
    raises(NonSquareMatrixError, lambda: linodesolve(A2, t, b=b2))

    raises(ValueError, lambda: linodesolve(A1[:2, :], t, b=b1))
    raises(ValueError, lambda: linodesolve(A1[:2, :], t, b=b1[:1]))

    # DOIT check
    A1 = Matrix([[1, -1], [1, -1]])
    b1 = Matrix([15*t - 10, -15*t - 5])
    sol1 = [C1 + C2*t + C2 - 10*t**3 + 10*t**2 + t*(15*t**2 - 5*t) - 10*t,
            C1 + C2*t - 10*t**3 - 5*t**2 + t*(15*t**2 - 5*t) - 5*t]
    assert constant_renumber(linodesolve(A1, t, b=b1, type="type2", doit=True),
                             variables=[t]) == sol1

    # Testing auto functionality
    func = [f(t), g(t)]
    eq = [Eq(f(t).diff(t) + g(t).diff(t), g(t) + t), Eq(g(t).diff(t), f(t))]
    ceq = canonical_odes(eq, func, t)
    (A1, A0), b = linear_ode_to_matrix(ceq[0], func, t, 1)
    A = A0
    sol = [C1*exp(-t/2 + sqrt(5)*t/2) + C2*exp(-sqrt(5)*t/2 - t/2) + exp(-t/2 + sqrt(5)*t/2)
           *Integral(-sqrt(5)*t*exp(-sqrt(5)*t/2 + t/2)/10 + t*exp(-sqrt(5)*t/2 + t/2)/2, t)
           + exp(-sqrt(5)*t/2 - t/2)*Integral(sqrt(5)*t*exp(t/2 + sqrt(5)*t/2)/10
           + t*exp(t/2 + sqrt(5)*t/2)/2, t), C1*exp(-t/2 + sqrt(5)*t/2)/2 + sqrt(5)
           *C1*exp(-t/2 + sqrt(5)*t/2)/2 - sqrt(5)*C2*exp(-sqrt(5)*t/2 - t/2)/2
           + C2*exp(-sqrt(5)*t/2 - t/2)/2 + exp(-t/2 + sqrt(5)*t/2)
           *Integral(-sqrt(5)*t*exp(-sqrt(5)*t/2 + t/2)/10 + t*exp(-sqrt(5)*t/2 + t/2)/2, t)/2
           + sqrt(5)*exp(-t/2 + sqrt(5)*t/2)*Integral(-sqrt(5)*t*exp(-sqrt(5)*t/2 + t/2)/10
           + t*exp(-sqrt(5)*t/2 + t/2)/2, t)/2 - sqrt(5)*exp(-sqrt(5)*t/2 - t/2)
           *Integral(sqrt(5)*t*exp(t/2 + sqrt(5)*t/2)/10 + t*exp(t/2 + sqrt(5)*t/2)/2, t)/2
           + exp(-sqrt(5)*t/2 - t/2)*Integral(sqrt(5)*t*exp(t/2 + sqrt(5)*t/2)/10
           + t*exp(t/2 + sqrt(5)*t/2)/2, t)/2]
    assert constant_renumber(linodesolve(A, t, b=b), variables=[t]) == sol

    # non-homogeneous term assumed to be 0
    sol1 =  [C1*exp(-t/2 + sqrt(5)*t/2) + C2*exp(-sqrt(5)*t/2 - t/2),
             C1*exp(-t/2 + sqrt(5)*t/2)/2 + sqrt(5)*C1*exp(-t/2 + sqrt(5)*t/2)/2 - sqrt(5)
             *C2*exp(-sqrt(5)*t/2 - t/2)/2 + C2*exp(-sqrt(5)*t/2 - t/2)/2]
    assert constant_renumber(linodesolve(A, t, type="type2"), variables=[t]) == sol1

    # Testing the Errors
    raises(ValueError, lambda: linodesolve(t+10, t))
    raises(ValueError, lambda: linodesolve(a*t, t))

    A1 = Matrix([[1, t], [-t, 1]])
    B1, _ = _is_commutative_anti_derivative(A1, t)
    raises(NonSquareMatrixError, lambda: linodesolve(A1[:, :1], t, B=B1))
    raises(ValueError, lambda: linodesolve(A1, t, B=1))

    A2 = Matrix([[t, t, t], [t, t, t], [t, t, t]])
    B2, _ = _is_commutative_anti_derivative(A2, t)
    raises(NonSquareMatrixError, lambda: linodesolve(A2, t, B=B2[:2, :]))
    raises(ValueError, lambda: linodesolve(A2, t, B=2))
    raises(ValueError, lambda: linodesolve(A2, t, B=B2, type="type31"))

    raises(ValueError, lambda: linodesolve(A1, t, B=B2))
    raises(ValueError, lambda: linodesolve(A2, t, B=B1))

    # Testing auto functionality
    func = [f(t), g(t)]
    eq = [Eq(f(t).diff(t), f(t) + t*g(t)), Eq(g(t).diff(t), -t*f(t) + g(t))]
    ceq = canonical_odes(eq, func, t)
    (A1, A0), b = linear_ode_to_matrix(ceq[0], func, t, 1)
    A = A0
    sol = [(C1/2 - I*C2/2)*exp(I*t**2/2 + t) + (C1/2 + I*C2/2)*exp(-I*t**2/2 + t),
           (-I*C1/2 + C2/2)*exp(-I*t**2/2 + t) + (I*C1/2 + C2/2)*exp(I*t**2/2 + t)]
    assert constant_renumber(linodesolve(A, t), variables=Tuple(*eq).free_symbols) == sol
    assert constant_renumber(linodesolve(A, t, type="type3"), variables=Tuple(*eq).free_symbols) == sol

    A1 = Matrix([[t, 1], [t, -1]])
    raises(NotImplementedError, lambda: linodesolve(A1, t))

    # Testing the Errors
    raises(ValueError, lambda: linodesolve(t+10, t, b=Matrix([t+1])))
    raises(ValueError, lambda: linodesolve(a*t, t, b=Matrix([log(t) + sin(t)])))

    raises(ValueError, lambda: linodesolve(Matrix([7*t]), t, b=t**2))
    raises(ValueError, lambda: linodesolve(Matrix([a + 10*log(t)]), t, b=log(t)*cos(t)))

    raises(ValueError, lambda: linodesolve(7*t, t, b=t**2))
    raises(ValueError, lambda: linodesolve(a*t**2, t, b=log(t) + sin(t)))

    A1 = Matrix([[1, t], [-t, 1]])
    b1 = Matrix([t, t ** 2])
    B1, _ = _is_commutative_anti_derivative(A1, t)
    raises(NonSquareMatrixError, lambda: linodesolve(A1[:, :1], t, b=b1))

    A2 = Matrix([[t, t, t], [t, t, t], [t, t, t]])
    b2 = Matrix([t, 1, t**2])
    B2, _ = _is_commutative_anti_derivative(A2, t)
    raises(NonSquareMatrixError, lambda: linodesolve(A2[:2, :], t, b=b2))

    raises(ValueError, lambda: linodesolve(A1, t, b=b2))
    raises(ValueError, lambda: linodesolve(A2, t, b=b1))

    raises(ValueError, lambda: linodesolve(A1, t, b=b1, B=B2))
    raises(ValueError, lambda: linodesolve(A2, t, b=b2, B=B1))

    # Testing auto functionality
    func = [f(x), g(x), h(x)]
    eq = [Eq(f(x).diff(x), x*(f(x) + g(x) + h(x)) + x),
          Eq(g(x).diff(x), x*(f(x) + g(x) + h(x)) + x),
          Eq(h(x).diff(x), x*(f(x) + g(x) + h(x)) + 1)]
    ceq = canonical_odes(eq, func, x)
    (A1, A0), b = linear_ode_to_matrix(ceq[0], func, x, 1)
    A = A0
    _x1 = exp(-3*x**2/2)
    _x2 = exp(3*x**2/2)
    _x3 = Integral(2*_x1*x/3 + _x1/3 + x/3 - Rational(1, 3), x)
    _x4 = 2*_x2*_x3/3
    _x5 = Integral(2*_x1*x/3 + _x1/3 - 2*x/3 + Rational(2, 3), x)
    sol = [
        C1*_x2/3 - C1/3 + C2*_x2/3 - C2/3 + C3*_x2/3 + 2*C3/3 + _x2*_x5/3 + _x3/3 + _x4 - _x5/3,
        C1*_x2/3 + 2*C1/3 + C2*_x2/3 - C2/3 + C3*_x2/3 - C3/3 + _x2*_x5/3 + _x3/3 + _x4 - _x5/3,
        C1*_x2/3 - C1/3 + C2*_x2/3 + 2*C2/3 + C3*_x2/3 - C3/3 + _x2*_x5/3 - 2*_x3/3 + _x4 + 2*_x5/3,
    ]
    assert constant_renumber(linodesolve(A, x, b=b), variables=Tuple(*eq).free_symbols) == sol
    assert constant_renumber(linodesolve(A, x, b=b, type="type4"),
                             variables=Tuple(*eq).free_symbols) == sol

    A1 = Matrix([[t, 1], [t, -1]])
    raises(NotImplementedError, lambda: linodesolve(A1, t, b=b1))

    # non-homogeneous term not passed
    sol1 = [-C1/3 - C2/3 + 2*C3/3 + (C1/3 + C2/3 + C3/3)*exp(3*x**2/2), 2*C1/3 - C2/3 - C3/3 + (C1/3 + C2/3 + C3/3)*exp(3*x**2/2),
            -C1/3 + 2*C2/3 - C3/3 + (C1/3 + C2/3 + C3/3)*exp(3*x**2/2)]
    assert constant_renumber(linodesolve(A, x, type="type4", doit=True), variables=Tuple(*eq).free_symbols) == sol1


@slow
def test_linear_3eq_order1_type4_slow():
    x, y, z = symbols('x, y, z', cls=Function)
    t = Symbol('t')

    f = t ** 3 + log(t)
    g = t ** 2 + sin(t)
    eq1 = (Eq(diff(x(t), t), (4 * f + g) * x(t) - f * y(t) - 2 * f * z(t)),
                Eq(diff(y(t), t), 2 * f * x(t) + (f + g) * y(t) - 2 * f * z(t)), Eq(diff(z(t), t), 5 * f * x(t) + f * y(
        t) + (-3 * f + g) * z(t)))
    with dotprodsimp(True):
        dsolve(eq1)


@slow
def test_linear_neq_order1_type2_slow1():
    i, r1, c1, r2, c2, t = symbols('i, r1, c1, r2, c2, t')
    x1 = Function('x1')
    x2 = Function('x2')

    eq1 = r1*c1*Derivative(x1(t), t) + x1(t) - x2(t) - r1*i
    eq2 = r2*c1*Derivative(x1(t), t) + r2*c2*Derivative(x2(t), t) + x2(t) - r2*i
    eq = [eq1, eq2]

    # XXX: Solution is too complicated
    [sol] = dsolve_system(eq, simplify=False, doit=False)
    assert checksysodesol(eq, sol) == (True, [0, 0])


# Regression test case for issue #9204
# https://github.com/sympy/sympy/issues/9204
@tooslow
def test_linear_new_order1_type2_de_lorentz_slow_check():
    m = Symbol("m", real=True)
    q = Symbol("q", real=True)
    t = Symbol("t", real=True)

    e1, e2, e3 = symbols("e1:4", real=True)
    b1, b2, b3 = symbols("b1:4", real=True)
    v1, v2, v3 = symbols("v1:4", cls=Function, real=True)

    eqs = [
        -e1*q + m*Derivative(v1(t), t) - q*(-b2*v3(t) + b3*v2(t)),
        -e2*q + m*Derivative(v2(t), t) - q*(b1*v3(t) - b3*v1(t)),
        -e3*q + m*Derivative(v3(t), t) - q*(-b1*v2(t) + b2*v1(t))
    ]
    sol = dsolve(eqs)
    assert checksysodesol(eqs, sol) == (True, [0, 0, 0])


# Regression test case for issue #14001
# https://github.com/sympy/sympy/issues/14001
@slow
def test_linear_neq_order1_type2_slow_check():
    RC, t, C, Vs, L, R1, V0, I0 = symbols("RC t C Vs L R1 V0 I0")
    V = Function("V")
    I = Function("I")
    system = [Eq(V(t).diff(t), -1/RC*V(t) + I(t)/C), Eq(I(t).diff(t), -R1/L*I(t) - 1/L*V(t) + Vs/L)]
    [sol] = dsolve_system(system, simplify=False, doit=False)

    assert checksysodesol(system, sol) == (True, [0, 0])


def _linear_3eq_order1_type4_long():
    x, y, z = symbols('x, y, z', cls=Function)
    t = Symbol('t')

    f = t ** 3 + log(t)
    g = t ** 2 + sin(t)

    eq1 = (Eq(diff(x(t), t), (4*f + g)*x(t) - f*y(t) - 2*f*z(t)),
           Eq(diff(y(t), t), 2*f*x(t) + (f + g)*y(t) - 2*f*z(t)), Eq(diff(z(t), t), 5*f*x(t) + f*y(
        t) + (-3*f + g)*z(t)))

    dsolve_sol = dsolve(eq1)
    dsolve_sol1 = [_simpsol(sol) for sol in dsolve_sol]

    x_1 = sqrt(-t**6 - 8*t**3*log(t) + 8*t**3 - 16*log(t)**2 + 32*log(t) - 16)
    x_2 = sqrt(3)
    x_3 = 8324372644*C1*x_1*x_2 + 4162186322*C2*x_1*x_2 - 8324372644*C3*x_1*x_2
    x_4 = 1 / (1903457163*t**3 + 3825881643*x_1*x_2 + 7613828652*log(t) - 7613828652)
    x_5 = exp(t**3/3 + t*x_1*x_2/4 - cos(t))
    x_6 = exp(t**3/3 - t*x_1*x_2/4 - cos(t))
    x_7 = exp(t**4/2 + t**3/3 + 2*t*log(t) - 2*t - cos(t))
    x_8 = 91238*C1*x_1*x_2 + 91238*C2*x_1*x_2 - 91238*C3*x_1*x_2
    x_9 = 1 / (66049*t**3 - 50629*x_1*x_2 + 264196*log(t) - 264196)
    x_10 = 50629 * C1 / 25189 + 37909*C2/25189 - 50629*C3/25189 - x_3*x_4
    x_11 = -50629*C1/25189 - 12720*C2/25189 + 50629*C3/25189 + x_3*x_4
    sol = [Eq(x(t), x_10*x_5 + x_11*x_6 + x_7*(C1 - C2)), Eq(y(t), x_10*x_5 + x_11*x_6), Eq(z(t), x_5*(
            -424*C1/257 - 167*C2/257 + 424*C3/257 - x_8*x_9) + x_6*(167*C1/257 + 424*C2/257 -
            167*C3/257 + x_8*x_9) + x_7*(C1 - C2))]

    assert dsolve_sol1 == sol
    assert checksysodesol(eq1, dsolve_sol1) == (True, [0, 0, 0])


@slow
def test_neq_order1_type4_slow_check1():
    f, g = symbols("f g", cls=Function)
    x = symbols("x")

    eqs = [Eq(diff(f(x), x), x*f(x) + x**2*g(x) + x),
           Eq(diff(g(x), x), 2*x**2*f(x) + (x + 3*x**2)*g(x) + 1)]
    sol = dsolve(eqs)
    assert checksysodesol(eqs, sol) == (True, [0, 0])


@slow
def test_neq_order1_type4_slow_check2():
    f, g, h = symbols("f, g, h", cls=Function)
    x = Symbol("x")

    eqs = [
        Eq(Derivative(f(x), x), x*h(x) + f(x) + g(x) + 1),
        Eq(Derivative(g(x), x), x*g(x) + f(x) + h(x) + 10),
        Eq(Derivative(h(x), x), x*f(x) + x + g(x) + h(x))
    ]
    with dotprodsimp(True):
        sol = dsolve(eqs)
    assert checksysodesol(eqs, sol) == (True, [0, 0, 0])


def _neq_order1_type4_slow3():
    f, g = symbols("f g", cls=Function)
    x = symbols("x")

    eqs = [
        Eq(Derivative(f(x), x), x*f(x) + g(x) + sin(x)),
        Eq(Derivative(g(x), x), x**2 + x*g(x) - f(x))
    ]
    sol = [
        Eq(f(x), (C1/2 - I*C2/2 - I*Integral(x**2*exp(-x**2/2 - I*x)/2 +
            x**2*exp(-x**2/2 + I*x)/2 + I*exp(-x**2/2 - I*x)*sin(x)/2 -
            I*exp(-x**2/2 + I*x)*sin(x)/2, x)/2 + Integral(-I*x**2*exp(-x**2/2
            - I*x)/2 + I*x**2*exp(-x**2/2 + I*x)/2 + exp(-x**2/2 -
            I*x)*sin(x)/2 + exp(-x**2/2 + I*x)*sin(x)/2, x)/2)*exp(x**2/2 +
            I*x) + (C1/2 + I*C2/2 + I*Integral(x**2*exp(-x**2/2 - I*x)/2 +
            x**2*exp(-x**2/2 + I*x)/2 + I*exp(-x**2/2 - I*x)*sin(x)/2 -
            I*exp(-x**2/2 + I*x)*sin(x)/2, x)/2 + Integral(-I*x**2*exp(-x**2/2
            - I*x)/2 + I*x**2*exp(-x**2/2 + I*x)/2 + exp(-x**2/2 -
            I*x)*sin(x)/2 + exp(-x**2/2 + I*x)*sin(x)/2, x)/2)*exp(x**2/2 -
            I*x)),
        Eq(g(x), (-I*C1/2 + C2/2 + Integral(x**2*exp(-x**2/2 - I*x)/2 +
            x**2*exp(-x**2/2 + I*x)/2 + I*exp(-x**2/2 - I*x)*sin(x)/2 -
            I*exp(-x**2/2 + I*x)*sin(x)/2, x)/2 -
            I*Integral(-I*x**2*exp(-x**2/2 - I*x)/2 + I*x**2*exp(-x**2/2 +
            I*x)/2 + exp(-x**2/2 - I*x)*sin(x)/2 + exp(-x**2/2 +
            I*x)*sin(x)/2, x)/2)*exp(x**2/2 - I*x) + (I*C1/2 + C2/2 +
            Integral(x**2*exp(-x**2/2 - I*x)/2 + x**2*exp(-x**2/2 + I*x)/2 +
            I*exp(-x**2/2 - I*x)*sin(x)/2 - I*exp(-x**2/2 + I*x)*sin(x)/2,
            x)/2 + I*Integral(-I*x**2*exp(-x**2/2 - I*x)/2 +
            I*x**2*exp(-x**2/2 + I*x)/2 + exp(-x**2/2 - I*x)*sin(x)/2 +
            exp(-x**2/2 + I*x)*sin(x)/2, x)/2)*exp(x**2/2 + I*x))
    ]

    return eqs, sol


def test_neq_order1_type4_slow3():
    eqs, sol = _neq_order1_type4_slow3()
    assert dsolve_system(eqs, simplify=False, doit=False) == [sol]
    # XXX: dsolve gives an error in integration:
    #     assert dsolve(eqs) == sol
    # https://github.com/sympy/sympy/issues/20155


@slow
def test_neq_order1_type4_slow_check3():
    eqs, sol = _neq_order1_type4_slow3()
    assert checksysodesol(eqs, sol) == (True, [0, 0])


@tooslow
@XFAIL
def test_linear_3eq_order1_type4_long_dsolve_slow_xfail():
    eq, sol = _linear_3eq_order1_type4_long()

    dsolve_sol = dsolve(eq)
    dsolve_sol1 = [_simpsol(sol) for sol in dsolve_sol]

    assert dsolve_sol1 == sol


@tooslow
def test_linear_3eq_order1_type4_long_dsolve_dotprodsimp():
    eq, sol = _linear_3eq_order1_type4_long()

    # XXX: Only works with dotprodsimp see
    # test_linear_3eq_order1_type4_long_dsolve_slow_xfail which is too slow
    with dotprodsimp(True):
        dsolve_sol = dsolve(eq)

    dsolve_sol1 = [_simpsol(sol) for sol in dsolve_sol]
    assert dsolve_sol1 == sol


@tooslow
def test_linear_3eq_order1_type4_long_check():
    eq, sol = _linear_3eq_order1_type4_long()
    assert checksysodesol(eq, sol) == (True, [0, 0, 0])


def test_dsolve_system():
    f, g = symbols("f g", cls=Function)
    x = symbols("x")
    eqs = [Eq(f(x).diff(x), f(x) + g(x)), Eq(g(x).diff(x), f(x) + g(x))]
    funcs = [f(x), g(x)]

    sol = [[Eq(f(x), -C1 + C2*exp(2*x)), Eq(g(x), C1 + C2*exp(2*x))]]
    assert dsolve_system(eqs, funcs=funcs, t=x, doit=True) == sol

    raises(ValueError, lambda: dsolve_system(1))
    raises(ValueError, lambda: dsolve_system(eqs, 1))
    raises(ValueError, lambda: dsolve_system(eqs, funcs, 1))
    raises(ValueError, lambda: dsolve_system(eqs, funcs[:1], x))

    eq = (Eq(f(x).diff(x), 12 * f(x) - 6 * g(x)), Eq(g(x).diff(x) ** 2, 11 * f(x) + 3 * g(x)))
    raises(NotImplementedError, lambda: dsolve_system(eq) == ([], []))

    raises(NotImplementedError, lambda: dsolve_system(eq, funcs=[f(x), g(x)]) == ([], []))
    raises(NotImplementedError, lambda: dsolve_system(eq, funcs=[f(x), g(x)], t=x) == ([], []))
    raises(NotImplementedError, lambda: dsolve_system(eq, funcs=[f(x), g(x)], t=x, ics={f(0): 1, g(0): 1}) == ([], []))
    raises(NotImplementedError, lambda: dsolve_system(eq, t=x, ics={f(0): 1, g(0): 1}) == ([], []))
    raises(NotImplementedError, lambda: dsolve_system(eq, ics={f(0): 1, g(0): 1}) == ([], []))
    raises(NotImplementedError, lambda: dsolve_system(eq, funcs=[f(x), g(x)], ics={f(0): 1, g(0): 1}) == ([], []))

def test_dsolve():

    f, g = symbols('f g', cls=Function)
    x, y = symbols('x y')

    eqs = [f(x).diff(x) - x, f(x).diff(x) + x]
    with raises(ValueError):
        dsolve(eqs)

    eqs = [f(x, y).diff(x)]
    with raises(ValueError):
        dsolve(eqs)

    eqs = [f(x, y).diff(x)+g(x).diff(x), g(x).diff(x)]
    with raises(ValueError):
        dsolve(eqs)


@slow
def test_higher_order1_slow1():
    x, y = symbols("x y", cls=Function)
    t = symbols("t")

    eq = [
        Eq(diff(x(t),t,t), (log(t)+t**2)*diff(x(t),t)+(log(t)+t**2)*3*diff(y(t),t)),
        Eq(diff(y(t),t,t), (log(t)+t**2)*2*diff(x(t),t)+(log(t)+t**2)*9*diff(y(t),t))
    ]
    sol, = dsolve_system(eq, simplify=False, doit=False)
    # The solution is too long to write out explicitly and checkodesol is too
    # slow so we test for particular values of t:
    for e in eq:
        res = (e.lhs - e.rhs).subs({sol[0].lhs:sol[0].rhs, sol[1].lhs:sol[1].rhs})
        res = res.subs({d: d.doit(deep=False) for d in res.atoms(Derivative)})
        assert ratsimp(res.subs(t, 1)) == 0


def test_second_order_type2_slow1():
    x, y, z = symbols('x, y, z', cls=Function)
    t, l = symbols('t, l')

    eqs1 = [Eq(Derivative(x(t), (t, 2)), t*(2*x(t) + y(t))),
            Eq(Derivative(y(t), (t, 2)), t*(-x(t) + 2*y(t)))]
    sol1 = [Eq(x(t), C1*airyai(t*(2 - I)**(Rational(1,3))) + C2*airyai(t*(2 + I)**(Rational(1,3)))
               + C3*airybi(t*(2 - I)**(Rational(1,3))) + C4*airybi(t*(2 + I)**(Rational(1,3)))),
            Eq(y(t), -I*C1*airyai(t*(2 - I)**(Rational(1,3))) + I*C2*airyai(t*(2 + I)**(Rational(1,3)))
               - I*C3*airybi(t*(2 - I)**(Rational(1,3))) + I*C4*airybi(t*(2 + I)**(Rational(1,3))))]
    assert dsolve(eqs1) == sol1
    assert checksysodesol(eqs1, sol1) == (True, [0, 0])


@tooslow
@XFAIL
def test_nonlinear_3eq_order1_type1():
    a, b, c = symbols('a b c')

    eqs = [
        a * f(x).diff(x) - (b - c) * g(x) * h(x),
        b * g(x).diff(x) - (c - a) * h(x) * f(x),
        c * h(x).diff(x) - (a - b) * f(x) * g(x),
    ]

    assert dsolve(eqs) # NotImplementedError


@XFAIL
def test_nonlinear_3eq_order1_type4():
    eqs = [
        Eq(f(x).diff(x), (2*h(x)*g(x) - 3*g(x)*h(x))),
        Eq(g(x).diff(x), (4*f(x)*h(x) - 2*h(x)*f(x))),
        Eq(h(x).diff(x), (3*g(x)*f(x) - 4*f(x)*g(x))),
    ]
    dsolve(eqs)  # KeyError when matching
    # sol = ?
    # assert dsolve_sol == sol
    # assert checksysodesol(eqs, dsolve_sol) == (True, [0, 0, 0])


@tooslow
@XFAIL
def test_nonlinear_3eq_order1_type3():
    eqs = [
        Eq(f(x).diff(x), (2*f(x)**2 - 3        )),
        Eq(g(x).diff(x), (4         - 2*h(x)   )),
        Eq(h(x).diff(x), (3*h(x)    - 4*f(x)**2)),
    ]
    dsolve(eqs)  # Not sure if this finishes...
    # sol = ?
    # assert dsolve_sol == sol
    # assert checksysodesol(eqs, dsolve_sol) == (True, [0, 0, 0])


@XFAIL
def test_nonlinear_3eq_order1_type5():
    eqs = [
        Eq(f(x).diff(x), f(x)*(2*f(x) - 3*g(x))),
        Eq(g(x).diff(x), g(x)*(4*g(x) - 2*h(x))),
        Eq(h(x).diff(x), h(x)*(3*h(x) - 4*f(x))),
    ]
    dsolve(eqs)  # KeyError
    # sol = ?
    # assert dsolve_sol == sol
    # assert checksysodesol(eqs, dsolve_sol) == (True, [0, 0, 0])


def test_linear_2eq_order1():
    x, y, z = symbols('x, y, z', cls=Function)
    k, l, m, n = symbols('k, l, m, n', Integer=True)
    t = Symbol('t')
    x0, y0 = symbols('x0, y0', cls=Function)

    eq1 = (Eq(diff(x(t),t), x(t) + y(t) + 9), Eq(diff(y(t),t), 2*x(t) + 5*y(t) + 23))
    sol1 = [Eq(x(t), C1*exp(t*(sqrt(6) + 3)) + C2*exp(t*(-sqrt(6) + 3)) - Rational(22, 3)), \
    Eq(y(t), C1*(2 + sqrt(6))*exp(t*(sqrt(6) + 3)) + C2*(-sqrt(6) + 2)*exp(t*(-sqrt(6) + 3)) - Rational(5, 3))]
    assert checksysodesol(eq1, sol1) == (True, [0, 0])

    eq2 = (Eq(diff(x(t),t), x(t) + y(t) + 81), Eq(diff(y(t),t), -2*x(t) + y(t) + 23))
    sol2 = [Eq(x(t), (C1*cos(sqrt(2)*t) + C2*sin(sqrt(2)*t))*exp(t) - Rational(58, 3)), \
    Eq(y(t), (-sqrt(2)*C1*sin(sqrt(2)*t) + sqrt(2)*C2*cos(sqrt(2)*t))*exp(t) - Rational(185, 3))]
    assert checksysodesol(eq2, sol2) == (True, [0, 0])

    eq3 = (Eq(diff(x(t),t), 5*t*x(t) + 2*y(t)), Eq(diff(y(t),t), 2*x(t) + 5*t*y(t)))
    sol3 = [Eq(x(t), (C1*exp(2*t) + C2*exp(-2*t))*exp(Rational(5, 2)*t**2)), \
    Eq(y(t), (C1*exp(2*t) - C2*exp(-2*t))*exp(Rational(5, 2)*t**2))]
    assert checksysodesol(eq3, sol3) == (True, [0, 0])

    eq4 = (Eq(diff(x(t),t), 5*t*x(t) + t**2*y(t)), Eq(diff(y(t),t), -t**2*x(t) + 5*t*y(t)))
    sol4 = [Eq(x(t), (C1*cos((t**3)/3) + C2*sin((t**3)/3))*exp(Rational(5, 2)*t**2)), \
    Eq(y(t), (-C1*sin((t**3)/3) + C2*cos((t**3)/3))*exp(Rational(5, 2)*t**2))]
    assert checksysodesol(eq4, sol4) == (True, [0, 0])

    eq5 = (Eq(diff(x(t),t), 5*t*x(t) + t**2*y(t)), Eq(diff(y(t),t), -t**2*x(t) + (5*t+9*t**2)*y(t)))
    sol5 = [Eq(x(t), (C1*exp((sqrt(77)/2 + Rational(9, 2))*(t**3)/3) + \
    C2*exp((-sqrt(77)/2 + Rational(9, 2))*(t**3)/3))*exp(Rational(5, 2)*t**2)), \
    Eq(y(t), (C1*(sqrt(77)/2 + Rational(9, 2))*exp((sqrt(77)/2 + Rational(9, 2))*(t**3)/3) + \
    C2*(-sqrt(77)/2 + Rational(9, 2))*exp((-sqrt(77)/2 + Rational(9, 2))*(t**3)/3))*exp(Rational(5, 2)*t**2))]
    assert checksysodesol(eq5, sol5) == (True, [0, 0])

    eq6 = (Eq(diff(x(t),t), 5*t*x(t) + t**2*y(t)), Eq(diff(y(t),t), (1-t**2)*x(t) + (5*t+9*t**2)*y(t)))
    sol6 = [Eq(x(t), C1*x0(t) + C2*x0(t)*Integral(t**2*exp(Integral(5*t, t))*exp(Integral(9*t**2 + 5*t, t))/x0(t)**2, t)), \
    Eq(y(t), C1*y0(t) + C2*(y0(t)*Integral(t**2*exp(Integral(5*t, t))*exp(Integral(9*t**2 + 5*t, t))/x0(t)**2, t) + \
    exp(Integral(5*t, t))*exp(Integral(9*t**2 + 5*t, t))/x0(t)))]
    s = dsolve(eq6)
    assert s == sol6   # too complicated to test with subs and simplify
    # assert checksysodesol(eq10, sol10) == (True, [0, 0])  # this one fails


def test_nonlinear_2eq_order1():
    x, y, z = symbols('x, y, z', cls=Function)
    t = Symbol('t')
    eq1 = (Eq(diff(x(t),t),x(t)*y(t)**3), Eq(diff(y(t),t),y(t)**5))
    sol1 = [
        Eq(x(t), C1*exp(-1/(-1/(2*(C2 + t)**(S(1)/4)) - I/(2*(C2 + t)**(S(1)/4))))),
        Eq(y(t), -1/(2*(C2 + t)**(S(1)/4)) - I/(2*(C2 + t)**(S(1)/4))),
        Eq(x(t), C1*exp(-1/(-1/(2*(C2 + t)**(S(1)/4)) + I/(2*(C2 + t)**(S(1)/4))))),
        Eq(y(t), -1/(2*(C2 + t)**(S(1)/4)) + I/(2*(C2 + t)**(S(1)/4))),
        Eq(x(t), C1*exp(-1/(1/(2*(C2 + t)**(S(1)/4)) - I/(2*(C2 + t)**(S(1)/4))))),
        Eq(y(t), 1/(2*(C2 + t)**(S(1)/4)) - I/(2*(C2 + t)**(S(1)/4))),
        Eq(x(t), C1*exp(-1/(1/(2*(C2 + t)**(S(1)/4)) + I/(2*(C2 + t)**(S(1)/4))))),
        Eq(y(t), 1/(2*(C2 + t)**(S(1)/4)) + I/(2*(C2 + t)**(S(1)/4)))
    ]
    assert dsolve(eq1) == sol1
    assert checksysodesol(eq1, sol1) == (True, [0, 0])

    eq2 = (Eq(diff(x(t),t), exp(3*x(t))*y(t)**3),Eq(diff(y(t),t), y(t)**5))
    sol2 = [
        Eq(x(t), -log(C1 + 3/(-1/(2*(C2 + t)**(S(1)/4)) - I/(2*(C2 + t)**(S(1)/4))))/3),
        Eq(y(t), -1/(2*(C2 + t)**(S(1)/4)) - I/(2*(C2 + t)**(S(1)/4))),
        Eq(x(t), -log(C1 + 3/(-1/(2*(C2 + t)**(S(1)/4)) + I/(2*(C2 + t)**(S(1)/4))))/3),
        Eq(y(t), -1/(2*(C2 + t)**(S(1)/4)) + I/(2*(C2 + t)**(S(1)/4))),
        Eq(x(t), -log(C1 + 3/(1/(2*(C2 + t)**(S(1)/4)) - I/(2*(C2 + t)**(S(1)/4))))/3),
        Eq(y(t), 1/(2*(C2 + t)**(S(1)/4)) - I/(2*(C2 + t)**(S(1)/4))),
        Eq(x(t), -log(C1 + 3/(1/(2*(C2 + t)**(S(1)/4)) + I/(2*(C2 + t)**(S(1)/4))))/3),
        Eq(y(t), 1/(2*(C2 + t)**(S(1)/4)) + I/(2*(C2 + t)**(S(1)/4)))
    ]
    assert dsolve(eq2) == sol2
    assert checksysodesol(eq2, sol2) == (True, [0, 0])

    eq3 = (Eq(diff(x(t),t), y(t)*x(t)), Eq(diff(y(t),t), x(t)**3))
    tt = Rational(2, 3)
    sol3 = [
        Eq(x(t), 6**tt/(6*(-sinh(sqrt(C1)*(C2 + t)/2)/sqrt(C1))**tt)),
        Eq(y(t), sqrt(C1 + C1/sinh(sqrt(C1)*(C2 + t)/2)**2)/3)]
    assert dsolve(eq3) == sol3
    # FIXME: assert checksysodesol(eq3, sol3) == (True, [0, 0])

    eq4 = (Eq(diff(x(t),t),x(t)*y(t)*sin(t)**2), Eq(diff(y(t),t),y(t)**2*sin(t)**2))
    sol4 = {Eq(x(t), -2*exp(C1)/(C2*exp(C1) + t - sin(2*t)/2)), Eq(y(t), -2/(C1 + t - sin(2*t)/2))}
    assert dsolve(eq4) == sol4
    # FIXME: assert checksysodesol(eq4, sol4) == (True, [0, 0])

    eq5 = (Eq(x(t),t*diff(x(t),t)+diff(x(t),t)*diff(y(t),t)), Eq(y(t),t*diff(y(t),t)+diff(y(t),t)**2))
    sol5 = {Eq(x(t), C1*C2 + C1*t), Eq(y(t), C2**2 + C2*t)}
    assert dsolve(eq5) == sol5
    assert checksysodesol(eq5, sol5) == (True, [0, 0])

    eq6 = (Eq(diff(x(t),t),x(t)**2*y(t)**3), Eq(diff(y(t),t),y(t)**5))
    sol6 = [
        Eq(x(t), 1/(C1 + 1/(-1/(2*(C2 + t)**(S(1)/4)) - I/(2*(C2 + t)**(S(1)/4))))),
        Eq(y(t), -1/(2*(C2 + t)**(S(1)/4)) - I/(2*(C2 + t)**(S(1)/4))),
        Eq(x(t), 1/(C1 + 1/(-1/(2*(C2 + t)**(S(1)/4)) + I/(2*(C2 + t)**(S(1)/4))))),
        Eq(y(t), -1/(2*(C2 + t)**(S(1)/4)) + I/(2*(C2 + t)**(S(1)/4))),
        Eq(x(t), 1/(C1 + 1/(1/(2*(C2 + t)**(S(1)/4)) - I/(2*(C2 + t)**(S(1)/4))))),
        Eq(y(t), 1/(2*(C2 + t)**(S(1)/4)) - I/(2*(C2 + t)**(S(1)/4))),
        Eq(x(t), 1/(C1 + 1/(1/(2*(C2 + t)**(S(1)/4)) + I/(2*(C2 + t)**(S(1)/4))))),
        Eq(y(t), 1/(2*(C2 + t)**(S(1)/4)) + I/(2*(C2 + t)**(S(1)/4)))
    ]
    assert dsolve(eq6) == sol6
    assert checksysodesol(eq6, sol6) == (True, [0, 0])


@slow
def test_nonlinear_3eq_order1():
    x, y, z = symbols('x, y, z', cls=Function)
    t, u = symbols('t u')
    eq1 = (4*diff(x(t),t) + 2*y(t)*z(t), 3*diff(y(t),t) - z(t)*x(t), 5*diff(z(t),t) - x(t)*y(t))
    sol1 = [Eq(4*Integral(1/(sqrt(-4*u**2 - 3*C1 + C2)*sqrt(-4*u**2 + 5*C1 - C2)), (u, x(t))),
        C3 - sqrt(15)*t/15), Eq(3*Integral(1/(sqrt(-6*u**2 - C1 + 5*C2)*sqrt(3*u**2 + C1 - 4*C2)),
        (u, y(t))), C3 + sqrt(5)*t/10), Eq(5*Integral(1/(sqrt(-10*u**2 - 3*C1 + C2)*
        sqrt(5*u**2 + 4*C1 - C2)), (u, z(t))), C3 + sqrt(3)*t/6)]
    assert [i.dummy_eq(j) for i, j in zip(dsolve(eq1), sol1)]
    # FIXME: assert checksysodesol(eq1, sol1) == (True, [0, 0, 0])

    eq2 = (4*diff(x(t),t) + 2*y(t)*z(t)*sin(t), 3*diff(y(t),t) - z(t)*x(t)*sin(t), 5*diff(z(t),t) - x(t)*y(t)*sin(t))
    sol2 = [Eq(3*Integral(1/(sqrt(-6*u**2 - C1 + 5*C2)*sqrt(3*u**2 + C1 - 4*C2)), (u, x(t))), C3 +
        sqrt(5)*cos(t)/10), Eq(4*Integral(1/(sqrt(-4*u**2 - 3*C1 + C2)*sqrt(-4*u**2 + 5*C1 - C2)),
        (u, y(t))), C3 - sqrt(15)*cos(t)/15), Eq(5*Integral(1/(sqrt(-10*u**2 - 3*C1 + C2)*
        sqrt(5*u**2 + 4*C1 - C2)), (u, z(t))), C3 + sqrt(3)*cos(t)/6)]
    assert [i.dummy_eq(j) for i, j in zip(dsolve(eq2), sol2)]
    # FIXME: assert checksysodesol(eq2, sol2) == (True, [0, 0, 0])


def test_C1_function_9239():
    t = Symbol('t')
    C1 = Function('C1')
    C2 = Function('C2')
    C3 = Symbol('C3')
    C4 = Symbol('C4')
    eq = (Eq(diff(C1(t), t), 9*C2(t)), Eq(diff(C2(t), t), 12*C1(t)))
    sol = [Eq(C1(t), 9*C3*exp(6*sqrt(3)*t) + 9*C4*exp(-6*sqrt(3)*t)),
           Eq(C2(t), 6*sqrt(3)*C3*exp(6*sqrt(3)*t) - 6*sqrt(3)*C4*exp(-6*sqrt(3)*t))]
    assert checksysodesol(eq, sol) == (True, [0, 0])


def test_dsolve_linsystem_symbol():
    eps = Symbol('epsilon', positive=True)
    eq1 = (Eq(diff(f(x), x), -eps*g(x)), Eq(diff(g(x), x), eps*f(x)))
    sol1 = [Eq(f(x), -C1*eps*cos(eps*x) - C2*eps*sin(eps*x)),
            Eq(g(x), -C1*eps*sin(eps*x) + C2*eps*cos(eps*x))]
    assert checksysodesol(eq1, sol1) == (True, [0, 0])
