[petsc-users] Reuse MUMPS factorization

[Bhargav Subramanya]

Thanks a lot, Matt.

On Sat, Mar 12, 2022 at 9:50 PM Matthew Knepley <knepley at gmail.com> wrote:

> On Sat, Mar 12, 2022 at 1:01 PM Bhargav Subramanya <
> bhargav.subramanya at kaust.edu.sa> wrote:
>
>> Dear All,
>>
>> I have the following two queries:
>>
>> 1. I am running simulations using MUMPS through a job submission system.
>> Since the job run time is limited, I need to restart the simulations
>> periodically. Since I am restarting the simulation with exactly the same
>> parameters, for instance, number of nodes, number of tasks per node, etc.,
>> is it possible to dump the matrix factors for the first time and reuse it
>> for the remaining restarts?
>>
>
> We do not have access to the MUMPS internals, so this is a MUMPS mailing
> list question I think.
>
>
>> 2. In the Ax=b solve, for now, the Matrix A doesn't change. However, if I
>> implement a slightly different time integration technique, matrix A changes
>> with each time step (sparsity pattern is still the same). Is it possible to
>> incorporate a modifying matrix A in the mumps solver?
>>
>
> You can preserve the symbolic factorization, and just carry out the
> numerical factorization. I believe we do this automatically if you just
> update the values.
>
>   Thanks,
>
>     Matt
>
>
>> Thanks,
>> Bhargav
>>
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>
>
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