cmath.py 文件源码

def cosh(x):
    _cosh_special = [
        [inf+nanj, None, inf, complex(float("inf"), -0.0), None, inf+nanj, inf+nanj],
        [nan+nanj, None, None, None, None, nan+nanj, nan+nanj],
        [nan, None, 1, complex(1, -0.0), None, nan, nan],
        [nan, None, complex(1, -0.0), 1, None, nan, nan],
        [nan+nanj, None, None, None, None, nan+nanj, nan+nanj],
        [inf+nanj, None, complex(float("inf"), -0.0), inf, None, inf+nanj, inf+nanj],
        [nan+nanj, nan+nanj, nan, nan, nan+nanj, nan+nanj, nan+nanj]
    ]

    z = _make_complex(x)

    if not isfinite(z):
        if math.isinf(z.imag) and not math.isnan(z.real):
            raise ValueError
        if math.isinf(z.real) and math.isfinite(z.imag) and z.imag != 0:
            if z.real > 0:
                return complex(math.copysign(inf, math.cos(z.imag)),
                               math.copysign(inf, math.sin(z.imag)))
            return complex(math.copysign(inf, math.cos(z.imag)),
                           -math.copysign(inf, math.sin(z.imag)))
        return _cosh_special[_special_type(z.real)][_special_type(z.imag)]

    if abs(z.real) > _LOG_LARGE_DOUBLE:
        x_minus_one = z.real - math.copysign(1, z.real)
        ret = complex(e * math.cos(z.imag) * math.cosh(x_minus_one),
                      e * math.sin(z.imag) * math.sinh(x_minus_one))
    else:
        ret = complex(math.cos(z.imag) * math.cosh(z.real),
                      math.sin(z.imag) * math.sinh(z.real))
    if math.isinf(ret.real) or math.isinf(ret.imag):
        raise OverflowError

    return ret