def function(self, x, y, amp, Ra, Rs, center_x=0, center_y=0):
        """

        :param x:
        :param y:
        :param amp:
        :param a:
        :param s:
        :param center_x:
        :param center_y:
        :return:
        """
        rho0 = self.lens.sigma2rho(amp, Ra, Rs)
        return self.lens.density_2d(x, y, rho0, Ra, Rs, center_x, center_y)
def function ( self , x , y , amp , Ra , Rs , center_x = 0 , center_y = 0 ) : rho0 = self . lens . sigma2rho ( amp , Ra , Rs ) return self . lens . density_2d ( x , y , rho0 , Ra , Rs , center_x , center_y )
:param x:
        :param y:
        :param amp:
        :param a:
        :param s:
        :param center_x:
        :param center_y:
        :return: