[Octave-bug-tracker] [bug #31352] interp2 broken for non-quadratic matrices when using cubic interpolation

[Gunnar Farnebäck]

Follow-up Comment #5, bug #31352 (project octave):

__splinen__ is the function used for the spline method in the existing
interp2.

newbicubic seems to work well computationally and is simpler and faster than
bicubic, as well as additionally supporting scattered interpolation points. It
does miss a bit of flexibility (meshgridded X, Y), however, and some bells and
whistles (extrapval and spline_alpha).

I haven't tried to run the latest newinterp2 yet but looking at the code it
isn't clear to me why you rewrite the input parsing. That part of the code
looks fine in the existing interp2. To me it seems easier to fix the
shortcomings in interp2 than to rewrite from scratch.

I attach a patch adding testcases for interp2 when called with vector-valued
Xi and Yi. A number of them are not currently passing.

/Gunnar

(file #21748)
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Additional Item Attachment:

File name: interp2_testcases.diff         Size:3 KB


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