libelefun.py 文件源码

def atan_newton(x, prec):
    if prec >= 100:
        r = math.atan(int((x>>(prec-53)))/2.0**53)
    else:
        r = math.atan(int(x)/2.0**prec)
    prevp = 50
    r = MPZ(int(r * 2.0**53) >> (53-prevp))
    extra_p = 50
    for wp in giant_steps(prevp, prec):
        wp += extra_p
        r = r << (wp-prevp)
        cos, sin = cos_sin_fixed(r, wp)
        tan = (sin << wp) // cos
        a = ((tan-rshift(x, prec-wp)) << wp) // ((MPZ_ONE<<wp) + ((tan**2)>>wp))
        r = r - a
        prevp = wp
    return rshift(r, prevp-prec)