[petsc-dev] MetSetBlockSize issue

[Barry Smith]

On Apr 24, 2012, at 1:39 PM, Mark F. Adams wrote:

> Now I'm getting this error with code like this:
> 
>      ierr = MatGetSubMatrix( Cmat, new_eq_indices, new_eq_indices, MAT_INITIAL_MATRIX, &mat );
>      CHKERRQ(ierr);
>      ierr = MatSetBlockSize( mat, cbs );      CHKERRQ(ierr);
> 
> and like this:
> 
>  ierr = MatPtAP( Amat_fine, Pold, MAT_INITIAL_MATRIX, 2.0, &Cmat ); CHKERRQ(ierr);
>  ierr = MatSetBlockSize( Cmat, cbs );      CHKERRQ(ierr);

   Right you cannot do this. The matrix already exists so you cannot now set its size.   

   Does Cmat have a block size of cbs

    What about Amat?   By default these routines should create the new matrix with the correct blocksize. 

    The harder part is if the blocksize of mat would be different than Cmat?

   Barry

> 
> Mark
> 
> On Apr 23, 2012, at 9:09 PM, Barry Smith wrote:
> 
>> 
>> Yes, look, for example how ex32 is handled at the bottom of the makefile.
>> 
>> Thanks
>> 
>>  Barry
>> 
>> On Apr 23, 2012, at 5:50 PM, Mark F. Adams wrote:
>> 
>>> 
>>> On Apr 23, 2012, at 5:59 PM, Barry Smith wrote:
>>> 
>>>> 
>>>> It was changed a while ago that MatSetBlockSize() couldn't be set after the matrix was full instantiated. I guess that example did not get fixed because it is not listed in the makefile to run in the makeall.
>>> 
>>> May I add it?
>>> 
>>>> 
>>>> I have fixed the example to call MatSetBlockSize() at a safe point.
>>>> 
>>>> Barry
>>>> 
>>>> On Apr 23, 2012, at 4:29 PM, Mark F. Adams wrote:
>>>> 
>>>>> ex55.c in ksp is failing with:
>>>>> 
>>>>> [0]PETSC ERROR: --------------------- Error Message ------------------------------------
>>>>> [0]PETSC ERROR: Arguments are incompatible!
>>>>> [0]PETSC ERROR: Cannot change block size 1 to 2!
>>>>> [0]PETSC ERROR: ------------------------------------------------------------------------
>>>>> 
>>>>> on this line 57 of ex55.c:
>>>>> 
>>>>> ierr = MatSetBlockSize(Amat,2);      CHKERRQ(ierr);
>>>>> 
>>>>> Any idea what happened here?  
>>>>> 
>>>>> Mark
>>>> 
>>>> 
>>> 
>> 
>> 
>