improved QR & Cholesky updating

[Jaroslav Hajek]

hi,

please consider the changeset:
http://artax.karlin.mff.cuni.cz/~hajej2am/ulozna/octave/qrupdate.diff
improving the qrupdate, qrinsert, qrdelete, qrshift, cholupdate,
cholinsert, choldelete, cholshift.

Summary of changes:
The current version 0 snapshot of qrupdate is deleted from libcruft,
instead qrupdate is a weak dependency.
If found, the above functions are defined, as well as corresponding
methods of QR & CHOL classes in liboctave.
All the updating routines now use more efficient column traversal of
matrices. qrupdate, qrinsert & qrdelete support batch
updating/insertion/deletion of columns (avoids repeated copying of the
matrices).
Maybe most importantly, rank-1 update & column insertion now support
economized factorization.

This (together with the earlier work) makes Octave significantly more
capable w.r.t. factorization updating than M*b.
Applications are optimization routines (fsolve, lsqnonneg).

cheers

-- 
RNDr. Jaroslav Hajek
computing expert
Aeronautical Research and Test Institute (VZLU)
Prague, Czech Republic
url: www.highegg.matfyz.cz