QR factorization

[Hong Zhang]

> >
> > does petsc currently support QR factorization?
No.

> > I saw that it is supposedly provided by an interface to the spooles
> > package, however the comment in MatQRFactorSymbolic_SeqAIJSpooles
> > that says
> > SETERRQ(PETSC_ERR_SUP,"QR Factorization is unsupported as the Spooles
> > implementation of QR is invalid.");
> > seems to imply that it is not working.

Spooles' QR doesn't work, so we gave up our interface to it.

Hong