def test_idiff():
# the use of idiff in ellipse also provides coverage
circ = x**2 + y**2 - 4
ans = -3*x*(x**2 + y**2)/y**5
assert ans == idiff(circ, y, x, 3).simplify()
assert ans == idiff(circ, [y], x, 3).simplify()
assert idiff(circ, y, x, 3).simplify() == ans
explicit = 12*x/sqrt(-x**2 + 4)**5
assert ans.subs(y, solve(circ, y)[0]).equals(explicit)
assert True in [sol.diff(x, 3).equals(explicit) for sol in solve(circ, y)]
assert idiff(x + t + y, [y, t], x) == -Derivative(t, x) - 1
def test_idiff():
# the use of idiff in ellipse also provides coverage
circ = x**2 + y**2 - 4
ans = -3*x*(x**2 + y**2)/y**5
assert ans == idiff(circ, y, x, 3).simplify()
assert ans == idiff(circ, [y], x, 3).simplify()
assert idiff(circ, y, x, 3).simplify() == ans
explicit = 12*x/sqrt(-x**2 + 4)**5
assert ans.subs(y, solve(circ, y)[0]).equals(explicit)
assert True in [sol.diff(x, 3).equals(explicit) for sol in solve(circ, y)]
assert idiff(x + t + y, [y, t], x) == -Derivative(t, x) - 1
def test_idiff():
x = Symbol('x', real=True)
y = Symbol('y', real=True)
t = Symbol('t', real=True)
f = Function('f')
g = Function('g')
# the use of idiff in ellipse also provides coverage
circ = x**2 + y**2 - 4
ans = -3*x*(x**2 + y**2)/y**5
assert ans == idiff(circ, y, x, 3).simplify()
assert ans == idiff(circ, [y], x, 3).simplify()
assert idiff(circ, y, x, 3).simplify() == ans
explicit = 12*x/sqrt(-x**2 + 4)**5
assert ans.subs(y, solve(circ, y)[0]).equals(explicit)
assert True in [sol.diff(x, 3).equals(explicit) for sol in solve(circ, y)]
assert idiff(x + t + y, [y, t], x) == -Derivative(t, x) - 1
assert idiff(f(x) * exp(f(x)) - x * exp(x), f(x), x) == (x + 1) * exp(x - f(x))/(f(x) + 1)
assert idiff(f(x) - y * exp(x), [f(x), y], x) == (y + Derivative(y, x)) * exp(x)
assert idiff(f(x) - y * exp(x), [y, f(x)], x) == -y + exp(-x) * Derivative(f(x), x)
assert idiff(f(x) - g(x), [f(x), g(x)], x) == Derivative(g(x), x)
def test_idiff():
x = Symbol('x', real=True)
y = Symbol('y', real=True)
t = Symbol('t', real=True)
f = Function('f')
g = Function('g')
# the use of idiff in ellipse also provides coverage
circ = x**2 + y**2 - 4
ans = 3*x*(-x**2 - y**2)/y**5
assert ans == idiff(circ, y, x, 3).simplify()
assert ans == idiff(circ, [y], x, 3).simplify()
assert idiff(circ, y, x, 3).simplify() == ans
explicit = 12*x/sqrt(-x**2 + 4)**5
assert ans.subs(y, solve(circ, y)[0]).equals(explicit)
assert True in [sol.diff(x, 3).equals(explicit) for sol in solve(circ, y)]
assert idiff(x + t + y, [y, t], x) == -Derivative(t, x) - 1
assert idiff(f(x) * exp(f(x)) - x * exp(x), f(x), x) == (x + 1) * exp(x - f(x))/(f(x) + 1)
assert idiff(f(x) - y * exp(x), [f(x), y], x) == (y + Derivative(y, x)) * exp(x)
assert idiff(f(x) - y * exp(x), [y, f(x)], x) == -y + exp(-x) * Derivative(f(x), x)
assert idiff(f(x) - g(x), [f(x), g(x)], x) == Derivative(g(x), x)