[petsc-users] reduce a MPIBAIJ matrix to seqaij format

[Hong Zhang]

shu guo :

>
> I am a new user of PetSc in fortran. I want to solve a ill conditioned
> matrix right now. And the matrix is now assembled as a MPIBAIJ matrix
> in a paralleled way. Now I want to use superlu (the serial direct
> solver) to solve it since its ill-conditioned characteristic. I tried
> MatConvert as
>
>           call MatConvert (Kmatem, MATSEQAIJ, MAT_INITIAL_MATRIX,
> Kmatemseq)
> and it gives me a segmentation error. Can anyone give me some advice?
>

 call MatConvert (Kmatem, MATAIJ, MAT_INITIAL_MATRIX, Kmatemseq)
or
call MatConvert (Kmatem, MATMPIAIJ, MAT_INITIAL_MATRIX, Kmatemseq)

>
> BTW, I am using Petsc 2.3.3-p15 version, which do not have Schur
> preconditioner for ill-conditioned matrix. Also hope someone can give
> me some advice on how to solve this kind of matrix based on this petsc
> version. Thanks a lot!
>

Petsc 2.3.3-p15 is too old. Please update to the latest petsc-3.3 and
configure it
with '--download-metis --download-parmetis --download-superlu
--download-superlu_dist'
Then use superlu_dist direct solver.

Hong

>
> Shu
>
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