[Octave-bug-tracker] [bug #41980] interp1: piecewise linear interpolation with discontinuities behaves differently

[Juan Pablo Carbajal]

Follow-up Comment #2, bug #41980 (project octave):

This might be a regression, introduced trying to fix the function for multiple
inputs. I am checking if I can fix this. However:

The data x,y doesn't define a function. There are two different outputs for
the same input. So linear interpolation is not defined, one could approximate,
but not interpolate. Now approximation is not the work of interp1
(optim-interp or regression functions would do the trick).

You case could be handled with "nearest", but what happens when there are more
than two values of the output for the same input?

I guess one could first check that the data is indeed discontinuous and not
noisy data, by checking that there are no more than 2 equal x values with
different y values. And then break the data into those points and produce
independent polynomials for each segment.

What does matlab do?



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