To call the same function for the same cubic spline interpolation as those also implemented in the module of "xyz_interpolated_reference_system" around lines 622~ lines 634 . "cubic" spline is clearly assigned.
Thank you for your input. I agree that we should do this. I have changed some other calls to InterpolatedUnivariateSpline as well, so now interp1d is used throughout.
To call the same function for the same cubic spline interpolation as those also implemented in the module of "xyz_interpolated_reference_system" around lines 622~ lines 634 . "cubic" spline is clearly assigned.