2: static char help[] = "Saves a dense matrix in a dense format (binary).\n\n";

  4:  #include <petscmat.h>

  6: int main(int argc,char **args)
  7: {
  8:   Mat            C;
  9:   PetscScalar    v;
 10:   PetscInt       i,j,m = 4,n = 4;
 12:   PetscMPIInt    rank,size;
 13:   PetscViewer    viewer;

 15:   PetscInitialize(&argc,&args,(char*)0,help);if (ierr) return ierr;
 16:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
 17:   MPI_Comm_size(PETSC_COMM_WORLD,&size);
 18:   PetscOptionsGetInt(NULL,NULL,"-m",&m,NULL);
 19:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);

 21:   /* PART 1:  Generate matrix, then write it in binary format */

 23:   /* Generate matrix */
 24:   MatCreateSeqDense(PETSC_COMM_WORLD,m,n,NULL,&C);
 25:   for (i=0; i<m; i++) {
 26:     for (j=0; j<n; j++) {
 27:       v    = i*m+j;
 28:       MatSetValues(C,1,&i,1,&j,&v,INSERT_VALUES);
 29:     }
 30:   }
 31:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
 32:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
 33:   PetscViewerBinaryOpen(PETSC_COMM_WORLD,"matrix.dat",FILE_MODE_WRITE,&viewer);
 34:   MatView(C,viewer);
 35:   PetscViewerDestroy(&viewer);
 36:   MatDestroy(&C);
 37:   PetscFinalize();
 38:   return ierr;
 39: }