Re: fixed points piecewise-linear fitting

[Ben Abbott]

On Mar 20, 2012, at 8:38 PM, Martin Helm wrote:

> Am 21.03.2012 00:25, schrieb Ben Abbott:
>> Using methods "linear" or "spline" give the same result. However,
>> using your approach "cubic"/"pchip" doesn't produce a minimum least
>> squares solution. I've attached a test script (go_ppfit.m) and both
>> ppfit.m (mine) and ppfit2.m (yours). I modified yours to support
>> weighted least squares. Ben
> Well that makes of course sense since f(a*x+b*y) = a*f(x)+b*f(y) is not
> valid for the pchip interpolants (I naively did not think about that
> case) while it is true for piecewise linear and spline interpolants.
> Thanks for having a further look and adjusting. Your function is very
> useful. Do you plan to add it to octave or octave forge?

I'll add some tests and improve the doc-string and then propose it be added 
Octave.

When I post to the developers lists, I'll cc you.

Ben