geomath.py 文件源码

def atanh(x):
    """atanh(x) (missing from python 2.5.2)"""

    if sys.version_info > (2, 6):
      return math.atanh(x)

    y = abs(x)                  # Enforce odd parity
    y = Math.log1p(2 * y/(1 - y))/2
    return -y if x < 0 else y