Re: [Libmesh-users] petsc issues

[Manav B. <manav@u.washington.edu>]

Thanks for your response Ben,

It is for a serial case. I am using MPI, but with a single processor.

Yes, I have checked the assembled, and stored matrices, and both are  
identical.

This happens only for a multiple dof case.

Thanks
Manav


On Jul 22, 2005, at 12:52 PM, KIRK, BENJAMIN (JSC-EG) (NASA) wrote:

> Is this problem for a serial or parallel case?
>
> The DOF numbering will be different in parallel when running on M  
> processors
> that when running on N processors.
>
> Can you assemble the matrix *and* read an old one from disk and  
> make sure
> the difference is 0?
>
> -Ben
>
> -----Original Message-----
> From: lib...@li...
> [mailto:lib...@li...] On Behalf Of  
> Manav Bhatia
> Sent: Friday, July 22, 2005 12:56 PM
> To: lib...@li...
> Subject: [Libmesh-users] petsc issues
>
>
> Hi
>      I am using libmesh with Petsc, and have implemented a feature
> where you can write the system matrix to disk via PetscBinaryViewer
> and then read it in later and then solve.
>
>      I have tested this with a heat transfer problem that has one dof
> per node, and it works fine.
>
>      However, when I do this for a problem with multiple dofs, like a
> structural problem, it is giving me all sorts of wierd results. This
> is wierd since just before the solve, I print the matrix to check if
> it was read alright, and there does not seem to be any problem with
> that.
>
>      The procedure I follow is
> -- to write
>              -- create petsc binary viewer
>              -- use ma view to write to the viewer
>              -- destroy petsc binary viewer
>
> -- to read
>              -- create petsc binary viewer
>              -- destroy the existing matrix with matrix destroy
>              -- read in the matrix with mat load
>              -- destroy petsc binary viewer
>
> After that, I use the solve function in the petsclinearsolver class.
>
> Any hints would be appreciated.
>
> Thanks
> Manav
>
>
>
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