[petsc-users] Use of DMDAVecGetArrayF90 and DMDAVecRestoreArrayF90

[Matthew Knepley]

On Tue, Nov 10, 2015 at 6:30 AM, TAY wee-beng <zonexo at gmail.com> wrote:

>
> On 10/11/2015 8:27 PM, Matthew Knepley wrote:
>
> On Tue, Nov 10, 2015 at 3:27 AM, TAY wee-beng <zonexo at gmail.com> wrote:
>
>> Hi,
>>
>> Inside my subroutine, I need to access the DA variable cu_types_array
>> frequently.
>>
>> So I need to call DMDAVecGetArrayF90 and DMDAVecRestoreArrayF90 before
>> and after frequently.
>>
>> Is this necessary? Can I call DMDAVecGetArrayF90 at the start and only
>> call DMDAVecRestoreArrayF90 towards the end, where I don't need to modify
>> the values of cu_types_array anymore?
>>
>> Will this cause memory corruption?
>>
>
> You cannot use any other vector operations before you have called Restore.
>
>
> Hi,
>
> What do you mean by vector operations? I will just be doing some maths
> operation to change the values in cu_types_array. Is that fine?
>

While you have the array, no other operation can change the values.

   Matt


>
>
> Also, must the array be restored using DMDAVecRestoreArrayF90 before
>> calling DMLocalToLocalBegin,DMLocalToLocalEnd?
>
>
> Yes.
>
>   Matt
>
>
>>
>> --
>> Thank you.
>>
>> Yours sincerely,
>>
>> TAY wee-beng
>>
>>
>
>
> --
> 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
>
>
>


-- 
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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