def _expand_coord(self, lat, lon, lmax_calc, degrees):
        """Evaluate the function at the coordinates lat and lon."""
        if self.normalization == '4pi':
            norm = 1
        elif self.normalization == 'schmidt':
            norm = 2
        elif self.normalization == 'unnorm':
            norm = 3
        elif self.normalization == 'ortho':
            norm = 4
        else:
            raise ValueError(
                "Normalization must be '4pi', 'ortho', 'schmidt', or " +
                "'unnorm'. Input value was {:s}"
                .format(repr(self.normalization)))

        if degrees is True:
            latin = lat
            lonin = lon
        else:
            latin = _np.rad2deg(lat)
            lonin = _np.rad2deg(lon)

        if type(lat) is not type(lon):
            raise ValueError('lat and lon must be of the same type. ' +
                             'Input types are {:s} and {:s}'
                             .format(repr(type(lat)), repr(type(lon))))

        if type(lat) is int or type(lat) is float or type(lat) is _np.float_:
            return _shtools.MakeGridPoint(self.coeffs, lat=latin, lon=lonin,
                                          lmax=lmax_calc, norm=norm,
                                          csphase=self.csphase)
        elif type(lat) is _np.ndarray:
            values = _np.empty_like(lat, dtype=float)
            for v, latitude, longitude in _np.nditer([values, latin, lonin],
                                                     op_flags=['readwrite']):
                v[...] = _shtools.MakeGridPoint(self.coeffs, lat=latitude,
                                                lon=longitude,
                                                lmax=lmax_calc, norm=norm,
                                                csphase=self.csphase)
            return values
        elif type(lat) is list:
            values = []
            for latitude, longitude in zip(latin, lonin):
                values.append(
                    _shtools.MakeGridPoint(self.coeffs, lat=latitude,
                                           lon=longitude,
                                           lmax=lmax_calc, norm=norm,
                                           csphase=self.csphase))
            return values
        else:
            raise ValueError('lat and lon must be either an int, float, ' +
                             'ndarray, or list. ' +
                             'Input types are {:s} and {:s}'
                             .format(repr(type(lat)), repr(type(lon))))
Evaluate the function at the coordinates lat and lon.