core.py 文件源码

def airy(th, B, lam=None):
    """
    Return the visibility value (unsquared), given
    - th the angular diameter in radian
    - B the baseline in m (alternatively in m/lambda)
    - lam the wavelength (alternatively None if B is already given as m/lambda)
    """
    if lam is None:
        x = np.pi*th*B
    else:
        x = np.pi*th*B/lam
    return 2*airyJ1(x)/x