Dear Jed, > This won't work either because MatGetLocalSubMatrix() does not work that > way and because MAT_REUSE_MATRIX requires that you have already used > that matrix for the given operation. > > You can create a MATNEST for the coupled matrix, but if you want it > fully assembled, you'll have to loop over the rows and call > MatSetValues. We have a partial implementation of MatConvert_Nest_AIJ > that, once completed, will provide a nicer interface for this.
Thank you, looping over the rows worked fine. I was just confused since the other method looked as if it was the right way to do this. Sorry for bothering you with this.. Jan
