[SciPy-Dev] Splines

[Pablo Winant]

On 21/02/2013 12:10, Robert Kern wrote:
> On Thu, Feb 21, 2013 at 10:33 AM, Pablo Winant <pablo.winant at gmail.com> wrote:
>> Hi,
>>
>> It's good to see people working in that direction. I will be more than
>> happy to participate if I can.
>>
>> As a user : I really wish I had a cubic spline interpolation with
>> natural bounding conditions (which implies linear extrapolation). This
>> is what is implemented in Matlab's griddedInterpolator and is missing
>> from the existing options in scipy (right?). Being able to evaluate the
>> derivatives is also a big advantage.
>>
>> As a developper : there is the Einspline library that has a
>> straightforward implementation in C. In particular, the representation
>> of spline objects (C structs) and the low-level API are very
>> straightforward and may be a good of inspiration. The library is
>> currently GPL, but the author told me it could be made BSD if some m4
>> macros are removed.
> Which macros? The only M4 macros I see are for autoconf, which
> shouldn't affect the license of the library itself and wouldn't be
> used anyways if Einspline were merged into scipy.
>
Well, I didn't know that. The author was indeed refering to the autoconf 
macros and said there was room to modernize the build system anyway. So 
it's not worth the effort ? That would be one problem less.

Not sure whether merging it as it is would be a good idea. There is a 
lot code repetition that make it hard to maintain. But it is 
conceptually very simple and the code it could be greatly simplified 
maybe using some code generation.