xref: /petsc/src/mat/tests/ex10.c (revision ebead697dbf761eb322f829370bbe90b3bd93fa3)
1 
2 static char help[] = "Tests repeated use of assembly for matrices.\n\n";
3 
4 #include <petscmat.h>
5 
6 int main(int argc,char **args)
7 {
8   Mat            C;
9   PetscInt       i,j,m = 5,n = 2,Ii,J;
10   PetscMPIInt    rank,size;
11   PetscScalar    v;
12 
13   PetscFunctionBeginUser;
14   PetscCall(PetscInitialize(&argc,&args,(char*)0,help));
15   PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD,&rank));
16   PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD,&size));
17   n    = 2*size;
18 
19   /* create the matrix for the five point stencil, YET AGAIN*/
20   PetscCall(MatCreate(PETSC_COMM_WORLD,&C));
21   PetscCall(MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,m*n,m*n));
22   PetscCall(MatSetFromOptions(C));
23   PetscCall(MatSetUp(C));
24   for (i=0; i<m; i++) {
25     for (j=2*rank; j<2*rank+2; j++) {
26       v = -1.0;  Ii = j + n*i;
27       if (i>0)   {J = Ii - n; PetscCall(MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES));}
28       if (i<m-1) {J = Ii + n; PetscCall(MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES));}
29       if (j>0)   {J = Ii - 1; PetscCall(MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES));}
30       if (j<n-1) {J = Ii + 1; PetscCall(MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES));}
31       v = 4.0; PetscCall(MatSetValues(C,1,&Ii,1,&Ii,&v,INSERT_VALUES));
32     }
33   }
34   PetscCall(MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY));
35   PetscCall(MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY));
36   for (i=0; i<m; i++) {
37     for (j=2*rank; j<2*rank+2; j++) {
38       v = 1.0;  Ii = j + n*i;
39       if (i>0)   {J = Ii - n; PetscCall(MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES));}
40       if (i<m-1) {J = Ii + n; PetscCall(MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES));}
41       if (j>0)   {J = Ii - 1; PetscCall(MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES));}
42       if (j<n-1) {J = Ii + 1; PetscCall(MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES));}
43       v = -4.0; PetscCall(MatSetValues(C,1,&Ii,1,&Ii,&v,INSERT_VALUES));
44     }
45   }
46   PetscCall(MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY));
47   PetscCall(MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY));
48 
49   PetscCall(MatView(C,PETSC_VIEWER_STDOUT_WORLD));
50 
51   PetscCall(MatDestroy(&C));
52   PetscCall(PetscFinalize());
53   return 0;
54 }
55 
56 /*TEST
57 
58    test:
59 
60 TEST*/
61