Create a pure diagonal matrix

[Shi Jin]

Hi,

I have a related question to the one above: what is the best way to create a purely diagonal matrix?
I am using
ierr = MatCreateMPIAIJ(comm,localM,localN,PETSC_DETERMINE,PETSC_DETERMINE,1, PETSC_NULL, 0, PETSC_NULL, &lumpedMP);CHKERRQ(ierr);
But I would think there might be a even better (faster/less memory) way?

I thought about the BDiag Matrix. I tried
ierr=MatCreateMPIBDiag(comm,localM,globalSize,globalSize,PETSC_NULL,1,      PETSC_NULL,PETSC_NULL,&lumpedM);CHKERRQ(ierr);
but not sure if it is done correctly. I am a little suspicious about those pointers I set as NULL.

If the above two are both correct, is there a better one?

Thank you very much.
 
--
Shi Jin, PhD




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