def d_alpha_dr(self, R, amp, sigma_x, sigma_y):
        """

        :param R:
        :param amp:
        :param sigma_x:
        :param sigma_y:
        :return:
        """
        c = 1. / (2 * sigma_x * sigma_y)
        A = self._amp2d_to_3d(amp, sigma_x, sigma_y) * np.sqrt(2/np.pi*sigma_x*sigma_y)
        return 1./R**2 * (-1 + (1 + 2*c*R**2) * np.exp(-c*R**2)) * A
def d_alpha_dr ( self , R , amp , sigma_x , sigma_y ) : c = 1. / ( 2 * sigma_x * sigma_y ) A = self . _amp2d_to_3d ( amp , sigma_x , sigma_y ) * np . sqrt ( 2 / np . pi * sigma_x * sigma_y ) return 1. / R ** 2 * ( - 1 + ( 1 + 2 * c * R ** 2 ) * np . exp ( - c * R ** 2 ) ) * A
:param R:
        :param amp:
        :param sigma_x:
        :param sigma_y:
        :return: