Hi, Octavers

The present implemented QR-routine in Octave uses

LAPACK (Fortran) with a C++ interface.

The usage is, say: [Q,R,P] = qr(A), which makes the

following decomposition: A*P = Q*R.

Is it possible to extend it so we get this

decomposition, Pr*Q'*A*Pc' = [R; 0]? If so, how can

this be achieved?

The best alternative is if anyone out there has a

function ready for usage. This might even be a good

update to the present QR-implementation?

It might be a solution to integrate the code of Thomas

Robey; SPARSEQR, which I've tried out. This routine

does a QR-factorization, which is described above. The

original code is written in C and C++ and is under

Library GPL license.

It has been used for rather large problems for Finite

Elements.

I've had some correspondance with Mr. Robey and it's

OK with him if I decided to integrate the sparseqr

routine of his in my RFSQP-routine in Octave-forge,

but only if I gave him credits.....And that's no

problem.

Is this routine (SPARSEQR) something for Octave of

Octave-forge?

Why I need it:

"I could integrate the code of his in my routine, but

since it would be dumb to implement this routine in

RFSQP, the SPARSEQR routine should be implemented in

main/sparse in octave-forge?

The reason why I'm interested in sparseqr, is that

RFSQP requires the Q matrix from the QR-routine, which

gives the possibility to solve a equality constrained

problem, using a "NULL SPACE" strategy. The reason is

that the Q-matrix gives an matrix with orthogonal

columns."

Any comments?

Cheers,

Ole J.

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