Remove knots fails with first and last knot

[jzwar]

Minimal example:

import splinepy as sp

# Create a simple spline
a = sp.BSpline([1],[[0,0,1,2,2]],[[0],[1],[2]])
# Remove first knot (optional)
a.remove_knots(0,[1]) # works just fine
# Error 
a.remove_knots(0,[0]) # Segfault
# Similarly
a.remove_knots(0,[2]) # Segfault

[deltaLuki]

If you compile splinepy in debug mode and run this, you will see that SplineLib throws the following exception:
ValueError: bsplinelib::parameter_spaces::ParameterSpace::RemoveKnot: Throws the following —> for dimension 0: for dimension0: Cannot insert or remove the first or last knot 2.000000 as only clamped knot vectors are allowed.

[jzwar]

Yes, but IMO, throwing exceptions only in debug mode is like an assertion. Exceptions should also be thrown if the user inputs faulty data. Especially, as we provide wheels that are built in release mode. Just some random segfault should never occur!

[jzwar]

As long as this is the case, the bug remains an issue

[deltaLuki]

Yes, but IMO, throwing exceptions only in debug mode is like an assertion. Exceptions should also be thrown if the user inputs faulty data. Especially, as we provide wheels that are built in release mode. Just some random segfault should never occur!

This is because #ifndef NDEBUG is used in the SplineLib. Do you think we should do our own checks inside splinepy? However, this would mean that the values are checked twice. Once in splinepy and once in SplineLib.

[jzwar]

@danielwolff1

[j042]

@danielwolff1

[danielwolff1]

I'll look into that after I'm back from Munich

[jzwar]

Maybe also a good start if knot insertion for C^(-1) is implemented ❤️ @j042