> On 25 Nov 2017, at 7:49 PM, Stefano Zampini <stefano.zamp...@gmail.com> wrote: > > Pierre, > > If you have access to the indices used to create the "unblocked" vecscatter, > you can then call ISCreateBlock and obtain the vecscatter you want.
OK, that’s a better start. > To obtain the garray, MatMPIAIJGetSeqAIJ Ah! I Ctrl+F’d the manual, but forgot to grep the sources. Thank you very much, Pierre >> On Nov 25, 2017, at 9:26 PM, Pierre Jolivet <pierre.joli...@enseeiht.fr >> <mailto:pierre.joli...@enseeiht.fr>> wrote: >> >> OK, so I guess I need to tinker around with VecScatterCreate. >> As a follow-up question, is there an easy way to get the “garray” from >> http://www.mcs.anl.gov/petsc/petsc-current/src/mat/impls/aij/mpi/mmaij.c.html#line105 >> >> <http://www.mcs.anl.gov/petsc/petsc-current/src/mat/impls/aij/mpi/mmaij.c.html#line105> >> to create the IS I need to feed to VecScatterCreate (after resizing by >> multiplying its size by bs and by shifting/inserting the proper indices)? >> Basically, I want to create the VecScatter for doing MatMult with a MATSHELL >> similar to a MATMPIBAIJ, and I want to re-use the information generated by >> the MatSetUpMultiply_MPIAIJ from a previously set up MATMPIAIJ with the same >> sparsity pattern. >> >> Thanks, >> Pierre >> >>> On 25 Nov 2017, at 4:43 PM, Smith, Barry F. <bsm...@mcs.anl.gov >>> <mailto:bsm...@mcs.anl.gov>> wrote: >>> >>> >>> Pierre, >>> >>> There is not. The block size is baked directly into the scatter data >>> structure so not trivial to change in a copy. >>> >>> Barry >>> >>> >>>> On Nov 25, 2017, at 7:41 AM, Pierre Jolivet <pierre.joli...@enseeiht.fr >>>> <mailto:pierre.joli...@enseeiht.fr>> wrote: >>>> >>>> Hello, >>>> Given a VecScatter inctx that operates on vectors x and y, I’d like to >>>> create a VecScatter inctx_bs with the same pattern, but that operators on >>>> vectors x_bs and y_bs with different block sizes than the original x and y >>>> (and that are thus of sizes n * bs). >>>> Is there an easy way to do this (I’m a VecScatter noob, sorry in advance >>>> if this is trivial)? >>>> >>>> Thank you, >>>> Pierre >>> >> >
