psf.py 文件源码

def jinc(r):
    ''' The Jinc function.

    Args:
        r (`number`): radial distance.

    Returns:
        `float`: the value of j1(x)/x for x != 0, 0.5 at 0.

    '''
    if r == 0:
        return 0.5
    else:
        return j1(r) / r