[petsc-users] Solving a linear system with symmetrical matrix

[Longmin RAN]

Thanks for the tips, Barry. I didn't specify --with-debugging=0 during
the configuration, I think this is the problem. I'll recompile petsc
accordingly to check on this.


Longmin

On Thu, Mar 24, 2011 at 1:30 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
> On Mar 24, 2011, at 5:26 AM, Longmin RAN wrote:
>
>> Hello everyone,
>>
>>
>> I use superlu inside petsc to solve linear systems with symmetrical
>> matrix. The solving time is at least twice longer than using superlu
>> directly.
>
>   How much of that time is in other parts of the code, not the actual superlu solver? Run the PETSc version with -log_summary; the times given in the lines
> MatFactorSymbolic, MatFactorNumerical, MatSolve (or some similar names) are the amount of time in Superlu. Compare those times to the superlu standalone solution time.
>
>    Did you ./configure PETSc with the option --with-debugging=0?
>
>   Barry
>
>
>
>> Since I'm new with Petsc, I didn't fine-tune much the petsc
>> solver, as I had done when using superlu directly. For example, in
>> superlu there are options like diagonal pivot
>> threshold(superlu_options_t.DiagPivotThresh), symmetric mode
>> (superlu_options_t.SymmetricMode), and column
>> permutation(superlu_options_t.ColPerm). Could anybody inform me about
>> the corresponding options in petsc? Thanks in advance.
>>
>> BTW, I tried the following options:
>>       MatSetOption(A, MAT_SYMMETRIC, PETSC_TRUE);
>>       MatSetOption(A, MAT_SYMMETRY_ETERNAL, PETSC_TRUE);
>> But it seems that these options weren't enough to reduce the solving
>> time sufficiently.
>>
>>
>> Best regards,
>>
>> - Longmin Ran
>
>