Looking for triangulator/interpolator

Grant Edwards grante at visi.com
Sat May 27 15:11:23 CEST 2006


On 2006-05-27, Travis E. Oliphant <oliphant.travis at ieee.org> wrote:

> Not that you made a bad choice.  I do wonder, how much of your
> difficulty was with the interface to the underlying fitpack
> routines.

I've no idea.  I had never done anything with splines before,
so it's quite possible I just wasn't doing things right.  I
never got it to work at all for non-gridded data (which is what
I needed).  Since it wasn't stable even for gridded data, I
more or less gave up.

> The interface is pretty involved as there are lots of
> parameter choices to the underlying routine.  It's very
> possible the interface is broken in some strange way.

I took a look at underlying Fortran code, but that made my
dizzy.

> Given how many people want to do interpolation.  I'm surprised
> nobody has looked into fixing up the fitpack routines that do
> it.  I suppose it's possible that the underlying fitpack
> routines are faulty in 2-d.
>
> Your examples will help in that study.
>
> Pearu made some nice class-based interfaces to fitpack in
> 2003.  They are in SciPy, but, it appears that people aren't
> making much use of them.  Did you try them?

Not that I remember.  

For that particular application, the interpolation had to be
done in real time, so a triangulation scheme turned out to be a
lot faster [with some constraints on the input data to make the
triangle search O(sqrt(N))].

-- 
Grant Edwards                   grante             Yow!  Are the STEWED PRUNES
                                  at               still in the HAIR DRYER?
                               visi.com            



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