about MatGetOwnershipRange

Barry Smith bsmith at mcs.anl.gov
Thu Jan 1 18:59:50 CST 2009

   For all Mats that PETSc provides including MatMFFD and MatShell()  
the assumption is satisfied.


On Jan 1, 2009, at 6:45 PM, Yujie wrote:

> I got a submatrix B from A in parallel mode. Because the rows  
> numbers of B in some processors of the cluster become 0, I want to  
> use MatGetOwnershipRange() to get the range in each processor. I  
> have checked this function, the description is as folllows:
> "
> MatGetOwnershipRange
> Returns the range of matrix rows owned by this processor, assuming  
> that the matrix is laid out with the first n1 rows on the first  
> processor, the next n2 rows on the second, etc. For certain parallel  
> layouts this range may not be well defined.
> "
> There is an assumption in this function, I am wondering whether I  
> can use this function here. if not, how to do it? thanks a lot.
> Yujie

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