[petsc-users] Question for time dependent problems

[Vijay S. Mahadevan]

Barry,

>>  Do not call MatZeroEntries on a freshly created matrix (that destroys
the preallocation pattern) so skip the MatZeroEntries the first time.
I found an earlier thread (
http://lists.mcs.anl.gov/pipermail/petsc-users/2011-April/008566.html) where
you said that it would not destroy the preallocation too.

So is the behavior different in the dev version ?

Vijay
On Jul 5, 2011 8:03 PM, "Barry Smith" <bsmith at mcs.anl.gov> wrote:
>
> On Jul 5, 2011, at 5:42 PM, Lisandro Dalcin wrote:
>
>> On 5 July 2011 17:35, Barry Smith <bsmith at mcs.anl.gov> wrote:
>>>
>>>> Beginning of a time step (1st implicit stage of RK scheme):
>>>> 1. Use MatZeroEntries on the preconditioner
>>>
>>> Do not call MatZeroEntries on a freshly created matrix (that destroys
the preallocation pattern) so skip the MatZeroEntries the first time.
>>>
>>
>> What do you mean? The OP said that the nonzero structure was set at
>> problem set up.
>
> Perhaps I miss understood. I interpreted that to mean the matrix was
provided with the correct preallocation information (and not the nonzero
structure) but yes if the nonzero structure is already set then one can call
MatZeroEntries() at that point.
>
> Perhaps we should "fix" MatZeroEntries()" to not screw up preallocation
information!
>
> Barry
>
>
>>
>> --
>> Lisandro Dalcin
>> ---------------
>> CIMEC (INTEC/CONICET-UNL)
>> Predio CONICET-Santa Fe
>> Colectora RN 168 Km 472, Paraje El Pozo
>> 3000 Santa Fe, Argentina
>> Tel: +54-342-4511594 (ext 1011)
>> Tel/Fax: +54-342-4511169
>
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