geomath.py 文件源码

def sincosd(x):
    """Compute sine and cosine of x in degrees."""

    r = math.fmod(x, 360)
    q = Math.nan if Math.isnan(r) else int(math.floor(r / 90 + 0.5))
    r -= 90 * q; r = math.radians(r)
    s = math.sin(r); c = math.cos(r)
    q = q % 4
    if q == 1:
      s, c =  c, -s
    elif q == 2:
      s, c = -s, -c
    elif q == 3:
      s, c = -c,  s
    # Remove the minus sign on -0.0 except for sin(-0.0).
    # On Windows 32-bit with python 2.7, math.fmod(-0.0, 360) = +0.0
    # (x, c) here fixes this bug.  See also Math::sincosd in the C++ library.
    # AngNormalize has a similar fix.
    s, c = (x, c) if x == 0 else (0.0+s, 0.0+c)
    return s, c