2: static char help[] = "Saves a rectangular sparse matrix to disk.\n\n";

  4: #include <petscmat.h>

  8: int main(int argc,char **args)
  9: {
 10:   Mat            A;
 12:   PetscInt       m = 100,n = 11,js[11],i,j,cnt;
 13:   PetscScalar    values[11];
 14:   PetscViewer    view;

 16:   PetscInitialize(&argc,&args,(char*)0,help);

 18:   MatCreateSeqAIJ(PETSC_COMM_WORLD,m,n,20,0,&A);

 20:   for (i=0; i<n; i++) values[i] = (PetscReal)i;

 22:   for (i=0; i<m; i++) {
 23:     cnt = 0;
 24:     if (i % 2) {
 25:       for (j=0; j<n; j += 2) {
 26:         js[cnt++] = j;
 27:       }
 28:     } else {
 29:       ;
 30:     }
 31:     MatSetValues(A,1,&i,cnt,js,values,INSERT_VALUES);
 32:   }
 33:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 34:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

 36:   PetscViewerBinaryOpen(PETSC_COMM_WORLD,"rect",FILE_MODE_WRITE,&view);
 37:   MatView(A,view);
 38:   PetscViewerDestroy(&view);

 40:   MatDestroy(&A);

 42:   PetscFinalize();
 43:   return 0;
 44: }