I concur that there should be a VecCreateWithArray() to automatically uses Seq vector for one process and MPI for multiple.
Barry > On Jan 15, 2019, at 3:01 AM, Dave May via petsc-dev <petsc-dev@mcs.anl.gov> > wrote: > > > > On Tue, 15 Jan 2019 at 08:50, Pierre Jolivet <pierre.joli...@enseeiht.fr> > wrote: > OK, I was wrong about MATAIJ, as Jed already pointed out. > What about BAIJ or Dense matrices? > > The preallocation methods for BAIJ and Dense both internally use > PetscTryMethod. > > > What about VecCreateMPIWithArray which seems to explicitly call > VecCreate_MPI_Private which explicitly sets the type to VECMPI > https://www.mcs.anl.gov/petsc/petsc-current/src/vec/vec/impls/mpi/pbvec.c.html#line522 > so that I cannot do a MatMult with a MATAIJ with a communicator of size 1? > > That looks problematic. > > Possibly there should either be an if statement in VecCreateMPIWithArray() > associated with the comm size, or there should be a new API > VecCreateWithArray() with the same args as VecCreateMPIWithArray. > > As a work around, you could add VecCreateWithArray() in your code base which > does the right thing. > > > > Thanks, > Pierre > >> On 15 Jan 2019, at 9:40 AM, Dave May <dave.mayhe...@gmail.com> wrote: >> >> >> >> On Tue, 15 Jan 2019 at 05:18, Pierre Jolivet via petsc-dev >> <petsc-dev@mcs.anl.gov> wrote: >> Cf. the end of my sentence: "(I know, I could switch to SeqAIJ_SeqDense, but >> that is not an option I have right now)” >> All my Mat are of type MATMPIX. Switching to MATX here as you suggested >> would mean that I need to add a bunch of if(comm_size == 1) >> MatSeqXSetPreallocation else MatMPIXSetPreallocation in the rest of my code, >> which is something I would rather avoid. >> >> Actually this is not the case. >> >> If you do as Hong suggests and use MATAIJ then the switch for comm_size for >> Seq or MPI is done internally to MatCreate and is not required in the user >> code. Additionally, in your preallocation routine, you can call safely both >> (without your comm_size if statement) >> MatSeqAIJSetPreallocation() >> and >> MatMPIAIJSetPreallocation() >> If the matrix type matches that expected by the API, then it gets executed. >> Otherwise nothing happens. >> >> This is done all over the place to enable the matrix type to be a run-time >> choice. >> >> For example, see here >> https://www.mcs.anl.gov/petsc/petsc-current/src/dm/impls/da/fdda.c.html#DMCreateMatrix_DA_3d_MPIAIJ >> and look at lines 1511 and 1512. >> >> Thanks, >> Dave >> >> >> >> >> >> Thanks, >> Pierre >> >>> On 14 Jan 2019, at 10:30 PM, Zhang, Hong <hzh...@mcs.anl.gov> wrote: >>> >>> Replace >>> ierr = MatSetType(A, MATMPIAIJ);CHKERRQ(ierr); >>> to >>> ierr = MatSetType(A, MATAIJ);CHKERRQ(ierr); >>> >>> Replace >>> ierr = MatSetType(B, MATMPIDENSE)i;CHKERRQ(ierr); >>> to >>> ierr = MatSetType(B, MATDENSE)i;CHKERRQ(ierr); >>> >>> Then add >>> MatSeqAIJSetPreallocation() >>> MatSeqDenseSetPreallocation() >>> >>> Hong >>> >>> On Mon, Jan 14, 2019 at 2:51 PM Pierre Jolivet via petsc-dev >>> <petsc-dev@mcs.anl.gov> wrote: >>> Hello, >>> Is there any chance to get MatMatMult_MPIAIJ_MPIDense and >>> MatTransposeMatMult_MPIAIJ_MPIDense fixed so that the attached program >>> could run _with a single_ process? (I know, I could switch to >>> SeqAIJ_SeqDense, but that is not an option I have right now) >>> >>> Thanks in advance, >>> Pierre >>> >> >
