Patrick,
Currently it is supported for MatSetValues_SeqAIJ() and
MatSetValues_MPIAIJ(). It is not handled for BAIJ and SBAIJ, the code while
crash with segv in those cases (since we don’t check for a valid v pointer
before use :-). But support could easily be added for BAIJ and SBAIJ with
just a few lines of code.
MatSetValuesBlocked() does not have this kind of support and adding it
would be cumbersome.
So I guess the question is does this “feature” add useful functionality
that makes the slightly more complex code worthwhile? Or is it an oddball thing
that should be removed? As the cool kids would say “what is the use case for
this feature?”.
I’m fine with adding support for BAIJ and SBAIJ and documenting it but
then I am also fine with removing it though I suspect it is used somewhere in
PETSc and thus that code would need to be located and changed if it is removed.
Barry
On Apr 11, 2014, at 12:51 PM, Patrick Lacasse <[email protected]>
wrote:
> Hi,
>
> I see that implementation of MatSetValues handles a special case when one
> passes a null pointer v=0.
> In this case, it is considered that all values are 0.
> But the documentation doesn't seems to talk about it :
> http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatSetValues.html
>
> Is it a feature that we can use?
> Should it be added to the doc?
>
> Patrick Lacasse
