[petsc-dev] PetscObjectStateIncrease in MatMult*

[Matthew Knepley]

On Sat, Oct 17, 2015 at 11:12 AM, Václav Hapla <vaclav.hapla at vsb.cz> wrote:

> Yes, exactly, MATSHELL.
> But if I am right, MatShellSetOperation sets mat->ops->mult pointer
> directly to user-specified MatMult unless MatShellUseScaledMethods has been
> called.
> So user must keep in mind he should call PetscObjectStateIncrease in his
> MatMult.
> I feel like this is something one would intuitively await from the
> interface function...
> It would be less error-prone for future and user-implemented MatTypes.
>

That removes the ability to leave the vector unchanged by an implementor.

   Matt


> Vaclav
>
> Dne 17.10.2015 v 17:58 Barry Smith napsal(a):
>
>> On Oct 17, 2015, at 5:10 AM, Václav Hapla <vaclav.hapla at vsb.cz> wrote:
>>>
>>> Hello,
>>> MatMult(), MatMultTranspose(), MatMultAdd(), MatMultTransposeAdd() and
>>> PCApply() belong to most common modifiers of Vec values.
>>> Maybe it would be nice if these routines called PetscObjectStateIncrease
>>> explicitly because of MATSHELL and such stuff.
>>> Thanks,
>>> Vaclav
>>>
>>     I assume you are suggesting this because users of MATSHELL or PCSHELL
>> may not realize they need to call PetscObjectStateIncrease() on the output
>> vector if they do not use VecGe/RestoretArray() to access the vector
>> entries? (VecRestoreArray() automatically increases the state)
>>
>>     What if we add it to MatMult_Shell(), MatMultTranspose_Shell(),
>> PCApply_Shell() and PCApplyTranspose_Shell()?  It looks like those are the
>> only ones where the state won't get increased automatically
>>
>>     Thanks for the suggestion,
>>
>>    Barry
>>
>> --
>>>
>>> Vaclav Hapla
>>> Junior researcher
>>> IT4Innovations <http://www.it4i.eu/>
>>>
>>>
>>>
> --
>
> Vaclav Hapla
> Junior researcher
> IT4Innovations <http://www.it4i.eu/>
>
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>
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> Vaclav Hapla
> IT4Innovations
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>
>
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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