mpmath package test failures

[slozier]

The following tests cases in the mpmath tests are failing:

• [ ] test_functions.areal_inverses
• [ ] test_functions.complex_inverse_functions
• [ ] test_gammazeta.rs_zeta
• [ ] test_interval.interval_complex

Looks like most of the failures are caused by cmath

test_functions.areal_inverses

assert cmath.asinh(-2).imag == 0

test_functions.complex_inverse_functions

assert cmath.acos(2).imag < 0
assert cmath.acos(2j).imag < 0
assert cmath.acos(-2j).imag > 0
assert cmath.atan(1+2j).real > 0
assert cmath.atan(-1-2j).real < 0

test_gammazeta.rs_zeta

try:
    cmath.sin(1e10j)
    assert False
except OverflowError:
    pass
else:
    assert False

try:
    cmath.cos(1e10j)
    assert False
except OverflowError:
    pass
else:
    assert False
return

test_interval.interval_complex

assert (2+2j) ** (-1) == (0.25-0.25j)
assert (2+2j) ** (-2) == -0.125j