2: static char help[] = "Tests repeated use of assembly for matrices.\n\n";

 4:  #include petscmat.h

  8: int main(int argc,char **args)
  9: {
 10:   Mat            C;
 11:   PetscInt       i,j,m = 5,n = 2,Ii,J;
 13:   PetscMPIInt    rank,size;
 14:   PetscScalar    v;


 17:   PetscInitialize(&argc,&args,(char *)0,help);
 18:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
 19:   MPI_Comm_size(PETSC_COMM_WORLD,&size);
 20:   n = 2*size;

 22:   /* create the matrix for the five point stencil, YET AGAIN*/
 23:   MatCreate(PETSC_COMM_WORLD,&C);
 24:   MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,m*n,m*n);
 25:   MatSetFromOptions(C);
 26:   for (i=0; i<m; i++) {
 27:     for (j=2*rank; j<2*rank+2; j++) {
 28:       v = -1.0;  Ii = j + n*i;
 29:       if (i>0)   {J = Ii - n; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 30:       if (i<m-1) {J = Ii + n; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 31:       if (j>0)   {J = Ii - 1; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 32:       if (j<n-1) {J = Ii + 1; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 33:       v = 4.0; MatSetValues(C,1,&Ii,1,&Ii,&v,INSERT_VALUES);
 34:     }
 35:   }
 36:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
 37:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
 38:   for (i=0; i<m; i++) {
 39:     for (j=2*rank; j<2*rank+2; j++) {
 40:       v = 1.0;  Ii = j + n*i;
 41:       if (i>0)   {J = Ii - n; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 42:       if (i<m-1) {J = Ii + n; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 43:       if (j>0)   {J = Ii - 1; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 44:       if (j<n-1) {J = Ii + 1; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 45:       v = -4.0; MatSetValues(C,1,&Ii,1,&Ii,&v,INSERT_VALUES);
 46:     }
 47:   }
 48:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
 49:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);

 51:   MatView(C,PETSC_VIEWER_STDOUT_WORLD);

 53:   MatDestroy(C);
 54:   PetscFinalize();
 55:   return 0;
 56: }