[petsc-users] Mat.createNest in petsc4py

[Amit Itagi]

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.

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
>
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