def sigma2fwhm(sigma):
sigma = np.asarray(sigma)<EOL>return np.sqrt(<NUM_LIT:8> * np.log(<NUM_LIT:2>)) * sigma<EOL>
Convert a sigma in a Gaussian kernel to a FWHM value.

    Parameters
    ----------
    sigma: float or numpy.array
       sigma value or values

    Returns
    -------
    fwhm: float or numpy.array
       fwhm values corresponding to `sigma` values