On Tue, Oct 2, 2012 at 5:25 AM, TAY wee-beng <zonexo at gmail.com> wrote:
> On 1/10/2012 4:39 PM, Jed Brown wrote: > > MatSetValues() inserts logically dense blocks. You are thinking of it as > inserting a bunch of arbitrary (row,col,value) but that's not how it works. > Read the man page and look at any of the examples. > > > If that's the case, is the 1st method I used the best way to insert the > matrix? > Yes, inserting one row at a time is typical. > > In other words, I already have the A matrix and b vector in Fortran > matrix, used for solving Ax = b. > > Is there a better or more efficient way of inserting the Fortran matrix > into PETSC's matrix? > > Thanks > > > On Mon, Oct 1, 2012 at 10:36 AM, TAY wee-beng <zonexo at gmail.com> wrote: > >> Hi, >> >> I'm trying to insert values into my PETSc matrix using MatSetValues. >> >> I tried using: >> >> *do ijk=ijk_xyz_sta,ijk_xyz_end** >> ** >> ** II = ijk - 1 !Fortran shift to 0-based** >> ** ** >> ** call >> MatSetValues(A_semi_xyz,1,II,7,int_semi_xyz(ijk,1:7),semi_mat_xyz(ijk,1:7),INSERT_VALUES,ierr) >> ** >> ** >> **end do* >> >> where ijk_xyz_sta/ijk_xyz_end are the starting/end index >> >> int_semi_xyz(ijk,1:7) stores the 7 column global indices >> >> semi_mat_xyz has the corresponding values. >> >> This work well but I'm trying to call MatSetValues in 1 statement, it >> failed. I tried: >> >> *do ijk = 1,ijk_xyz_end-ijk_xyz_sta** >> ** >> ** rows(ijk) = ijk_xyz_sta + ijk - 1** !to get row's global indices >> ** ** >> **end do** >> ** >> **call >> MatSetValues(A_semi_xyz,ijk_xyz_end-ijk_xyz_sta,rows,7,int_semi_xyz(ijk_xyz_sta+1:ijk_xyz_end,1:7),semi_mat_xyz(ijk_xyz_sta+1:ijk_xyz_end,1:7),INSERT_VALUES,ierr) >> * >> >> but when I use MatView, the values are in the wrong locations. >> >> May I know what's wrong? >> >> Thanks >> >> -- >> Yours sincerely, >> >> TAY wee-beng >> >> > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20121002/fc7b9e25/attachment.html>
