[petsc-users] Setting block size for MPI vectors

[Vijay S. Mahadevan]

>    We've debated back and forth this. The WithArray() version has to take the block size because it has to instantiate the vector at that point because it needs a place to put the array pointer.

Understood.  But since VecCreateMPI is creating the vector completely
too, should it not know the block size a-priori ? The long winded way
is general enough that I like it but the specific API would be
incomplete without giving this ability to the user IMO.

> I don't think that's ever going to be a general solution, so "raw" Vec
> creation will always matter too.

And I agree with Jed. Even if DM helps make a user's life easier,
there are so many applications that just want to create a matrix,
vector and let petsc solve the system without needing to worry about
creating a DM Wrapper and hop another indirection.


On Tue, Aug 27, 2013 at 5:50 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
> Barry Smith <bsmith at mcs.anl.gov> writes:
>>    Our longer term plan is that most PETSc programs would not directly
>>    be creating Vecs and Mats with VecCreate… or MatCreate… rather they
>>    would create a DM and then use the DM object to create the
>>    appropriately laid out vectors and matrices for the users and
>>    solvers with DMCreateGlobalVector() etc.
>
> I don't think that's ever going to be a general solution, so "raw" Vec
> creation will always matter too.