2: static char help[] = "Tests copying an AIJ matrix.\n\n";

 4:  #include petscmat.h

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

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

 17:   /* create the matrix for the five point stencil, YET AGAIN*/
 18:   MatCreateSeqAIJ(PETSC_COMM_SELF,m*n,m*n,5,PETSC_NULL,&C);
 19:   for (i=0; i<m; i++) {
 20:     for (j=0; j<n; j++) {
 21:       v = -1.0;  Ii = j + n*i;
 22:       if (i>0)   {J = Ii - n; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 23:       if (i<m-1) {J = Ii + n; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 24:       if (j>0)   {J = Ii - 1; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 25:       if (j<n-1) {J = Ii + 1; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 26:       v = 4.0; MatSetValues(C,1,&Ii,1,&Ii,&v,INSERT_VALUES);
 27:     }
 28:   }
 29:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
 30:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);

 32:   MatConvert(C,MATSAME,MAT_INITIAL_MATRIX,&A);

 34:   for (i=0; i<m; i++) {
 35:     for (j=0; j<n; j++) {
 36:       v = -1.0;  Ii = j + n*i;
 37:       if (i>0)   {J = Ii - n; MatSetValues(A,1,&Ii,1,&J,&v,ADD_VALUES);}
 38:       if (i<m-1) {J = Ii + n; MatSetValues(A,1,&Ii,1,&J,&v,ADD_VALUES);}
 39:       if (j>0)   {J = Ii - 1; MatSetValues(A,1,&Ii,1,&J,&v,ADD_VALUES);}
 40:       if (j<n-1) {J = Ii + 1; MatSetValues(A,1,&Ii,1,&J,&v,ADD_VALUES);}
 41:       v = 4.0; MatSetValues(A,1,&Ii,1,&Ii,&v,ADD_VALUES);
 42:     }
 43:   }
 44:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 45:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

 47:   MatView(A,PETSC_VIEWER_STDOUT_SELF);

 49:   MatDestroy(C);
 50:   MatDestroy(A);
 51:   PetscFinalize();
 52:   return 0;
 53: }