def derivatives(self, x, y, coeffs, beta, center_x=0, center_y=0):
        """
        returns df/dx and df/dy of the function
        """
        shapelets = self._createShapelet(coeffs)
        r, phi = param_util.cart2polar(x, y, center=np.array([center_x, center_y]))
        alpha1_shapelets, alpha2_shapelets = self._alphaShapelets(shapelets, beta)
        f_x = self._shapeletOutput(r, phi, beta, alpha1_shapelets)
        f_y = self._shapeletOutput(r, phi, beta, alpha2_shapelets)
        return f_x, f_y
def derivatives ( self , x , y , coeffs , beta , center_x = 0 , center_y = 0 ) : shapelets = self . _createShapelet ( coeffs ) r , phi = param_util . cart2polar ( x , y , center = np . array ( [ center_x , center_y ] ) ) alpha1_shapelets , alpha2_shapelets = self . _alphaShapelets ( shapelets , beta ) f_x = self . _shapeletOutput ( r , phi , beta , alpha1_shapelets ) f_y = self . _shapeletOutput ( r , phi , beta , alpha2_shapelets ) return f_x , f_y
returns df/dx and df/dy of the function