I have been going through the implementation of B-splines, and I observe that whenever it comes to clamping, it's usually mentioned that we must repeat the end knots $p+1$ times for a spline of degree $p$. However, without a very clear explanation.
Going a little further, it can be attributed to the derivative being 0, but that also seems like a result rather than cause. I have also seen that splines can be considered internal to the convex hull, and all the points being identical cause it to tangentially start from it.
I am referring to this resource quite often - MTU Course Notes
Could you suggest a more intuitive or visual understanding for the clamping process?