[petsc-users] Custom vector owenrship ranges

[Matthew Knepley]

On Tue, Mar 18, 2014 at 11:00 AM, Mohammad Bahaa
<m.bahaa.eldein at gmail.com>wrote:

> I used
> call VecCreateMPIWithArray(PETSC_COMM_WORLD,1,nc,ncall,myx,xall,ierr)
>
> however, when I use process 0 to write a file containing the combined
> values (the xall vector), the values seem not to be updated by some
> processes, eventhough I use PetscBarrier, in other words, values locally
> owned by processes 0 and 2 are ok, but those owned by process 1 & 3 aren't !
>

For collective writes, use VecView() or -vec_view

   Matt


> On Tue, Mar 18, 2014 at 3:43 PM, Mohammad Bahaa <m.bahaa.eldein at gmail.com>wrote:
>
>> the second approach of the MPI vector did it for me, thanks
>>
>>
>> On Tue, Mar 18, 2014 at 3:20 PM, Mohammad Bahaa <m.bahaa.eldein at gmail.com
>> > wrote:
>>
>>> Forgive me as my expression "sum up" was misguiding or misplaced, I
>>> didn't mean to literally sum the values in the vectors, I meant I want to
>>> put all values from each local vector into one global vector that can be
>>> accessed by all processes, "COMM_WORLD" communicator for instance
>>>
>>>
>>> On Tue, Mar 18, 2014 at 3:09 PM, Matthew Knepley <knepley at gmail.com>wrote:
>>>
>>>> On Tue, Mar 18, 2014 at 7:53 AM, Mohammad Bahaa <
>>>> m.bahaa.eldein at gmail.com> wrote:
>>>>
>>>>> I'm using "PETSC_COMM_SELF" communicator for running n serial
>>>>> independent processes, I need to sum up a certain vector from the n
>>>>> processes in one vector, however, vectors involved in each process vary in
>>>>> size, and I couldn't find any function to define custom ownership ranges,
>>>>> so assuming I have a 4 processes run with each computing an "x" vector as
>>>>> follows:
>>>>>
>>>>> 1. process (1) with x of length 51
>>>>> 2. process (2) with x of length 49
>>>>> 3. process (3) with x of length 52
>>>>> 4. process (4) with x of length 48
>>>>>
>>>>
>>>> Let your local length be n, so that on proc 3 n== 52. Then
>>>>
>>>>   VecCreate(comm, &v);
>>>>   VecSetSizes(v, n, PETSC_DETERMINE);
>>>>   VecSetFromOptions(v);
>>>>   <fill up v>
>>>>   VecSum(v, &sum);
>>>>
>>>> You could also make a parallel Vec from your Seq vecs:
>>>>
>>>>   VecGetArray(lv, &array);
>>>>   VecCreateMPIWithArray(comm, 1, n, PETSC_DETERMINE, array, &v);
>>>>
>>>>   Thanks,
>>>>
>>>>      Matt
>>>>
>>>>
>>>>> The processes sum up to 100 elements, when I define a vector "x_all"
>>>>> of size "100" with "PETSC_COMM_WORLD" communicator, the ownership
>>>>> ranges are equal, which isn't the case, how to customize them ?
>>>>>
>>>>> --
>>>>> Mohamamd Bahaa ElDin
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> 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
>>>>
>>>
>>>
>>>
>>> --
>>> Mohamamd Bahaa ElDin
>>>
>>
>>
>>
>> --
>> Mohamamd Bahaa ElDin
>>
>
>
>
> --
> Mohamamd Bahaa ElDin
>



-- 
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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20140318/188a335b/attachment.html>