Is it possible to specify the 'order' of a smoothing spline?
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Mohammad Shojaei Arani on 14 Aug 2022
I need to use smoothing splines. The matlab command 'csaps' can only be used for the case of a cubic smoothing
spline. On the other hand, the command '[...] = spaps(x,y,tol,,m)' might be helpful to choose the order. But, there are a
range of difficulties with this command. First, we have to specify the tolerance 'tol' (I do not like to specify anything like tolerance or
smoothing parameter and woulds like the algorithm to choose the default). Second, m can only be 1(linear case), 2(cubic case), or 3 (
the quintic case). In my work I really need to use the 'quadratic smoothin splines'.
If I would like to do 'spline interpolation', instead, I could use the command 'spapi(k,x,y)' and choose k=3 for the case of quadratic spline interpolation. Is there a similar matlab command for smoothing splines? Something like 'spaps(k,x,y)' with no extra inputs like 'tolerance' or 'smoothing parameter' or 'weight'?
If MATLAB does not have the above-mentioned capability then this is a really 'annoying problem' which could be easily prevented by
the developers of spline toolbox. You might think that cubic smoothing splines are sufficient and there really is no need for a parabolic smoothing splines. If you are interested I can give you some important mathematical problems which really need the quadratic smoothing splines.
Thanks in advance!