[petsc-users] Mat.createNest in petsc4py

[Matthew Knepley]

On Fri, Apr 4, 2014 at 12:40 PM, Amit Itagi <gcfrai at gmail.com> wrote:

> I tried the equivalent version with petsc in C++:
>
>  Mat subA[4];
>  Mat A;
>   ...
>  MatCreateNest(comm,2,NULL,2,NULL,subA,&A);
>
> I did not face any issues. I am trying to map it to petsc4py.
>

Notice that petsc4py does not have the two 2 arguments. It must get these
from the array...

   Matt


> Amit
>
>
>
> On Fri, Apr 4, 2014 at 12:29 PM, Matthew Knepley <knepley at gmail.com>wrote:
>
>> On Fri, Apr 4, 2014 at 12:27 PM, Amit Itagi <gcfrai at gmail.com> wrote:
>>
>>> I need to use the createNest for some application. I am trying it out on
>>> a toy program. I created four 6x6 AIJ matrices on two processes. I am
>>> trying to create a nest using
>>>
>>> A=PETSc.Mat()
>>> A.createNest([mA11,mA12,mA21,mA22])
>>>
>>
>> I have never run this using petsc4py, but if it were me I would make it
>> take a 2D array.
>>
>>    Matt
>>
>>
>>> I get the following error:
>>>
>>>     A.createNest([mA11,mA12,mA21,mA22])
>>>   File "Mat.pyx", line 409, in petsc4py.PETSc.Mat.createNest
>>> (src/petsc4py.PETSc.c:85554)
>>>     A.createNest([mA11,mA12,mA21,mA22])
>>>   File "Mat.pyx", line 409, in petsc4py.PETSc.Mat.createNest
>>> (src/petsc4py.PETSc.c:85554)
>>>   File "Mat.pyx", line 197, in petsc4py.PETSc.Mat.__getitem__
>>> (src/petsc4py.PETSc.c:81516)
>>>   File "Mat.pyx", line 197, in petsc4py.PETSc.Mat.__getitem__
>>> (src/petsc4py.PETSc.c:81516)
>>>   File "petscmat.pxi", line 870, in petsc4py.PETSc.mat_getitem
>>> (src/petsc4py.PETSc.c:24830)
>>>   File "petscmat.pxi", line 870, in petsc4py.PETSc.mat_getitem
>>> (src/petsc4py.PETSc.c:24830)
>>> TypeError: 'int' object is not iterable
>>> TypeError: 'int' object is not iterable
>>>
>>> Any ideas ?
>>>
>>> Also, is the following the correct way of setting the nest to a 2x2
>>> block ?
>>>
>>> ix=PETSc.IS()
>>> ix.CreateGeneral([0,1])
>>> A.createNest([mA11,mA12,mA21,mA22],isrows=ix,iscols=ix)
>>>
>>> Thanks
>>>
>>> Amit
>>>
>>>
>>>
>>
>>
>> --
>> 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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