'One dimensional Sersic profile function.'

@classmethod
def evaluate(cls, r, amplitude, r_eff, n):

    if (cls._gammaincinv is None):
        try:
            from scipy.special import gammaincinv
            cls._gammaincinv = gammaincinv
        except ValueError:
            raise ImportError(u'Sersic1D    model    requires    scipy    >    0.11.')
    return (amplitude * np.exp(((- cls._gammaincinv((2 * n), 0.5)) * (((r / r_eff) ** (1 / n)) - 1))))
