[petsc-users] MUMPS with symmetric matrices

[Gianluca Meneghello]

That is correct... I will try with -pc_type cholesky and use
MatTransposeMatMult.

Using cholesky I do not need to specify mumps as a solver, am I right?

A is a linearization of the Navier Stokes equation.

Thanks!

Gianluca

On Wed, Nov 4, 2015 at 12:46 PM, Jed Brown <jed at jedbrown.org> wrote:

> Gianluca Meneghello <gianmail at gmail.com> writes:
>
> > Dear all,
> >
> > I am trying to solve a linear system for a symmetric matrix with MUMPS.
> >
> > Is there a way to tell MUMPS that the matrix is indeed symmetric?
> >
> > The way I build the matrix is
> >
> > Mat A,AT,ATA
> > MatHermitianTranspose(A,MAT_INITIAL_MATRIX,&AT);
> > MatMatMult(AT,A,MAT_INITIAL_MATRIX,7,&ATA);
> > MatSetOption(ATA,MAT_SYMMETRY_ETERNAL,PETSC_TRUE);
> >
> > but MUMPS returns
> >
> > L U Solver for unsymmetric matrices
>
> You're probably using -pc_type lu rather than -pc_type cholesky.
>
> > Of course, any suggestion of a better/more efficient way to build ATA or
> > store only half of it, that is more than welcome.
>
> Where does A come from?
>
> There is MatTransposeMatMult()
>
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