On Mon, Dec 7, 2015 at 12:11 AM, Bibrak Qamar <[email protected]> wrote:
> Hi, > > I am trying to apply a function on each element of a matrix. The function > is the sigmoid function which transforms each element of the matrix. > This pattern is problematic because we have no good way to indicate to PETSc that only 1 process intends to change a value, so after each SetValues() you need an assembly. You want something like MatChop(), http://www.mcs.anl.gov/petsc/petsc-current/src/mat/utils/axpy.c.html#MatChop Thanks, Matt > I am trying to approach it like this but get error. What could be the > problem? Or is there a better way to do this? > > int sigmoid(Mat x){ > printf("in sigmoid\n"); > > PetscErrorCode ierr; > PetscInt Istart, Iend, Ii, Ji, rows, cols; > > PetscScalar v = 0.0; > ierr = MatGetOwnershipRange(x,&Istart,&Iend);CHKERRQ(ierr); > MatGetSize(x,&rows,&cols); > > for (Ii=Istart; Ii<Iend; Ii++) { > for (Ji=0; Ji<cols; Ji++){ > ierr = MatGetValues(x,1,&Ii,1,&Ji,&v);CHKERRQ(ierr); > v = mysigmoid(v); > ierr = MatSetValues(x,1,&Ii,1,&Ji,&v,INSERT_VALUES);CHKERRQ(ierr); > } > } > > MatAssemblyBegin(x,MAT_FINAL_ASSEMBLY); > MatAssemblyEnd(x,MAT_FINAL_ASSEMBLY); > > > MatView(x,PETSC_VIEWER_STDOUT_WORLD); > } > > > error msg is: > > [0]PETSC ERROR: --------------------- Error Message > -------------------------------------------------------------- > [0]PETSC ERROR: Object is in wrong state > [0]PETSC ERROR: Not for unassembled matrix > [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html > for trouble shooting. > [0]PETSC ERROR: Petsc Release Version 3.6.3, Dec, 03, 2015 > [ > [0]PETSC ERROR: #1 MatGetValues() line 1780 in > /gpfs/home/petsc-3.6.3/src/mat/interface/matrix.c > [0]PETSC ERROR: #2 sigmoid() line 21 in neural.c > > > Thanks > Bibrak Qamar > > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener
