1: !
  2: !
  3: !  Tests MatDenseGetArray()
  4: !
  5: #include <petsc/finclude/petscmat.h>
  6: program main
  7:   use petscmat
  8:   implicit none

 10:   Mat A
 11:   PetscErrorCode ierr
 12:   PetscInt i, j, iar(1), jar(1)
 13:   PetscInt, parameter :: m = 3, n = 2
 14:   PetscScalar v(1)
 15:   PetscScalar, pointer :: array(:, :)
 16:   PetscMPIInt rank
 17:   integer :: ashape(2)
 18:   character(len=80) :: string

 20:   PetscCallA(PetscInitialize(ierr))
 21: !
 22: ! Create a parallel dense matrix shared by all processors
 23: !
 24:   PetscCallA(MatCreateDense(PETSC_COMM_WORLD, PETSC_DECIDE, PETSC_DECIDE, m, n, PETSC_NULL_SCALAR_ARRAY, A, ierr))

 26: !
 27: ! Set values into the matrix. All processors set all values.
 28: !
 29:   do i = 0, m - 1
 30:     iar(1) = i
 31:     do j = 0, n - 1
 32:       jar(1) = j
 33:       v(1) = 9.0/real(i + j + 1)
 34:       PetscCallA(MatSetValues(A, 1_PETSC_INT_KIND, iar, 1_PETSC_INT_KIND, jar, v, INSERT_VALUES, ierr))
 35:     end do
 36:   end do

 38:   PetscCallA(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY, ierr))
 39:   PetscCallA(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY, ierr))

 41: !
 42: ! Print the matrix to the screen
 43: !
 44:   PetscCallA(MatView(A, PETSC_VIEWER_STDOUT_WORLD, ierr))

 46: !
 47: ! Print the local matrix shape to the screen for each rank
 48: !
 49:   PetscCallA(MatDenseGetArray(A, array, ierr))
 50:   PetscCallMPIA(MPI_Comm_rank(PETSC_COMM_WORLD, rank, ierr))
 51:   ashape = shape(array)
 52:   write (string, '("[", i0, "]", " shape (", i0, ",", i0, ")", a1)') rank, ashape(1), ashape(2), new_line('a')
 53:   PetscCallA(PetscSynchronizedPrintf(PETSC_COMM_WORLD, string, ierr))
 54:   PetscCallA(PetscSynchronizedFlush(PETSC_COMM_WORLD, PETSC_STDOUT, ierr))
 55:   PetscCallA(MatDenseRestoreArray(A, array, ierr))
 56: !
 57: ! Free the space used by the matrix
 58: !
 59:   PetscCallA(MatDestroy(A, ierr))
 60:   PetscCallA(PetscFinalize(ierr))
 61: end

 63: !/*TEST
 64: !
 65: !   test:
 66: !      nsize: 2
 67: !      filter: sort -b
 68: !      filter_output: sort -b
 69: !
 70: !TEST*/