[SciPy-dev] Wrapping band matrices

[Arnd Baecker]

Hi,

I would like to contribute f2py generated
wrappers for the LAPACK routines
  dgbrfs,  dgbtrf, dgbtrs, dsbev, dsbevd, dsbevx
which deal with symmetric band matrices.

Originally they were developed with Numeric
and the old f2py.

At this point I have two questions:

a) before the function signature looked like:

    dsbev - Function signature:
      w,z,info = dsbev(ab,[compute_v,lower,ldab,overwrite_ab])

   but now it is

    dsbev - Function signature:
      w,z,info = dsbev(ab,[compute_v,lower,ldab])

   I.e.: `overwrite_ab` is missing.

   What has to be done to get this again?

b) What would be the best approach for the integration
   into scipy?

   The present status is at
      http://www.physik.tu-dresden.de/~baecker/python/band.zip

   The routines work "stand-alone"
     python setup.py build
     python tests/test_band.py
   and  (after more clean-up/documentation)_
   might_ be a good example/framework
   for others to add further LAPACK routines.
   In particular I think it is easier to test new stuff separately
   than to directly integrate it into
   scipy/Lib/linalg/generic_flapack.pyf

   Would it make sense to add this to the scipy sandbox at some point?
   (I would prefer to leave the final integration
    into scipy/Lib/linalg/* to a real expert...)

   In any case, before this, the next steps are:
     - do the <tchar=s,d>sbev stuff for all routines
       in generic_band.pyf
     - address FIXMEs in generic_band.pyf
     - add unit tests for all routines
       (only one example is given at the moment)

Many thanks,

Arnd