[petsc-users] SLEPc Eigenvalue problem - Zero Pivot

[venkatesh g]

Actually krylovschur it is giving excellent results when my B matrix is not
singular.

This time my B matrix is large with very little non-zero entries. There are
entire rows and columns with zeros.
So other than MUMPS, which I will try now, is there another way ?

Venkatesh

On Thu, May 14, 2015 at 11:01 PM, Jose E. Roman <jroman at dsic.upv.es> wrote:

> This has nothing to do with ARPACK.
>
>
> El 14/05/2015, a las 19:29, venkatesh g escribió:
>
> > I am trying to use ARPACK. will it help?
> >
> > It is not linking Arpack however, when I give ./configure
> --with-arpack-dir=..... command from manual.
> >
> > Venkatesh
> >
> > On Thu, May 14, 2015 at 10:54 PM, Jose E. Roman <jroman at dsic.upv.es>
> wrote:
> >
> > El 14/05/2015, a las 19:13, venkatesh g escribió:
> >
> > > Hi,
> > > 1. I am not calling EPSSetFromOptions in source code. I am using the
> ex7.c given in the SLEPc webpage.
> > > 2. A-matrix is not singular. Only B is singular.
> > > 3. I will try with MUMPS.
> > > 4. Matrix sizes are same as in Matlab. If B is not singular it is
> giving same result as Matlab, but if B is singular it gives the zero pivot
> issue which Matlab doesnt give.
> > > So is there a way ?
> > >
> >
> > The ex7.c example calls EPSSetFromOptions(). If it is not called, then
> command-line options are ignored.
> >
> > It is strange that you get zero pivots when factoring A-sigma*B for
> different values of sigma. Try with MUMPS.
> >
> > Jose
> >
> >
>
>
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