cmath.py 文件源码

def acos(x):
    _acos_special = [
        [3*pi/4+infj, pi+infj, pi+infj, pi-infj, pi-infj, 3*pi/4-infj, nan+infj],
        [pi/2+infj, None, None, None, None, pi/2-infj, nan+nanj],
        [pi/2+infj, None, None, None, None, pi/2-infj, pi/2+nanj],
        [pi/2+infj, None, None, None, None, pi/2-infj, pi/2+nanj],
        [pi/2+infj, None, None, None, None, pi/2-infj, nan+nanj],
        [pi/4+infj, infj, infj, 0.0-infj, 0.0-infj, pi/4-infj, nan+infj],
        [nan+infj, nan+nanj, nan+nanj, nan+nanj, nan+nanj, nan-infj, nan+nanj]
    ]

    z = _make_complex(x)

    if not isfinite(z):
        return _acos_special[_special_type(z.real)][_special_type(z.imag)]

    if abs(z.real) > _LARGE_DOUBLE or abs(z.imag) > _LARGE_DOUBLE:
        if z.real < 0:
            imag = -math.copysign(math.log(math.hypot(z.real/2, z.imag/2)) +
                                  2 * _LOG_2, z.imag)
        else:
            imag = math.copysign(math.log(math.hypot(z.real/2, z.imag/2)) +
                                 2 * _LOG_2, -z.imag)
        return complex(math.atan2(abs(z.imag), z.real), imag)

    s1 = sqrt(complex(1.0 - z.real, -z.imag))
    s2 = sqrt(complex(1.0 + z.real, z.imag))
    return complex(2 * math.atan2(s1.real, s2.real),
                   math.asinh(s2.real*s1.imag - s2.imag*s1.real))