[petsc-users] Exploiting symmetry with direct solvers

[Hong]

David ,

> I'm curious about how to do a symmetric LDL^T factorization (instead of
> LU) with MUMPS and SuperLU. Based on this example:
>
>
> http://www.mcs.anl.gov/petsc/petsc-3.4/src/ksp/ksp/examples/tutorials/ex52.c.html
>
> my understanding is as follows:
>
> - With MUMPS I gather that we need to specify:
>
> MatSetOption(A,MAT_SPD,PETSC_TRUE);
> PCSetType(pc,PCCHOLESKY);
>
> I guess "-pc_type cholesky" on the command line is equivalent to the
> PCSetType call, right? Is specifying MAT_SPD required in order for MUMPS to
> do an LDL^T factorization?
>
Mumps supports Cholesky factorization for symmetric, and symmetric+spd
matrices.  You may consult mumps user manual.

>
> - I gather that SuperLU doesn't provide a symmetric factorization.
>
SuperLU does not support Cholesky factorization.

Hong
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