On 09/08/2013 03:57 PM, Jed Brown wrote:
In the second call, ISCreateBlock looks at the array of block indices of
length n2 starting from inputindices+n1. That references
inputindices[n1], which is off the end of the array you created above.
Simply extending that array won't work either because you can't describe
the starting point correctly for one "block" of different length. I.e.,
if inputindices[1] == 1, then the second call above would be creating
the index set
{sz2, sz2+1,..., 2*sz2-1}
This should be obvious if you look at ISView().
Yes, but then there is a problem with my understanding of the block
structure.
What I would like to do at the end is to create a first block of size
1490 and then create a block of size 2432 and stack these. This is how
the original system is built up.
Of what if I use the below code,
PetscInt sz1 = 1490, sz2 = 2432;
/* ----- */
PetscInt n1=1, n2=1,
inputindices1[]={0}, inputindices2[]={1}; /* block size is 2 */
ISCreateBlock(PETSC_COMM_SELF,sz1,n1,inputindices1,
PETSC_COPY_VALUES,&is_row1);
ISCreateBlock(PETSC_COMM_SELF,sz2,n2,inputindices2,
PETSC_COPY_VALUES,&is_row2);
Because if I look at
http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/IS/ISCreateBlock.html
I am getting the impression that bs and n are the same and on top idx is
the global block number of the large matrix blocks.
I will look at the below option in a minute.
If your vectors are ordered so that the blocks are separate and
contiguous (as opposed to interlaced in some way), I suggest using
ISCreateStride(PETSC_COMM_SELF,sz1,0,1,&is_row1);
ISCreateStride(PETSC_COMM_SELF,sz2,sz1,1,is_row2);
