def fitted(self, fid=0):
        """Test if enough Levenberg-Marquardt loops have been done.

        It returns True if no improvement possible.

        :param fid: the id of the sub-fitter (numerical)
        """
        self._checkid(fid)
        return not (self._fitids[fid]["fit"] > 0
                    or self._fitids[fid]["fit"] < -0.001)
Test if enough Levenberg-Marquardt loops have been done.

        It returns True if no improvement possible.

        :param fid: the id of the sub-fitter (numerical)