[SciPy-Dev] ARPACK fixes before 0.9

[Pauli Virtanen]

Hi,

The Arpack interface in Scipy needs some fixes, which would be useful to 
get in for Scipy 0.9. I have them in a branch here:

	https://github.com/pv/scipy-work/tree/bug/1313-arpack

Comments would be appreciated (esp. from David who wrote the original 
interface). I'm going to merge them probably the next W/E unless 
objections arise.

Bugfixes:

- Raise ArpackNoConvergence when ARPACK iteration does not converge.
  Previously, there was no way to know if convergence was obtained.

- Fix a bug in return value extraction from dneupd, which resulted
  to invalid eigenvectors/eigenvalues being returned on non-convergence.

- Allow complex matrices in the sparse SVD. It's a naive approach, 
  but probably still better than nothing.

Other changes:

- Rename routines eigen* -> eigs* to avoid shadowing the "eigen" module.
  "eigs" is also the name for the equivalent routines in Octave/Matlab.

- Remove the ``speigs`` ARPACK interface. It does not seem to make sense
  two have two different interfaces to the same library.

- Un-deprecate .dot() method of sparse matrixes -- ndarrays also have
  it, so it makes sense to retain it.

-- 
Pauli Virtanen