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, m, n, iar(1), jar(1)
 13:   PetscInt one
 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:   m = 3
 22:   n = 2
 23:   one = 1
 24: !
 25: !      Create a parallel dense matrix shared by all processors
 26: !
 27:   PetscCallA(MatCreateDense(PETSC_COMM_WORLD, PETSC_DECIDE, PETSC_DECIDE, m, n, PETSC_NULL_SCALAR_ARRAY, A, ierr))

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

 41:   PetscCallA(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY, ierr))
 42:   PetscCallA(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY, ierr))

 44: !
 45: !       Print the matrix to the screen
 46: !
 47:   PetscCallA(MatView(A, PETSC_VIEWER_STDOUT_WORLD, ierr))

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

 66: !/*TEST
 67: !
 68: !   test:
 69: !      nsize: 2
 70: !      filter: sort -b
 71: !      filter_output: sort -b
 72: !
 73: !TEST*/