Actual source code: ex14.c
2: static char help[] = "Tests sequential and parallel MatGetRow() and MatRestoreRow().\n";
4: #include <petscmat.h>
6: int main(int argc,char **args)
7: {
8: Mat C;
9: PetscInt i,j,m = 5,n = 5,Ii,J,nz,rstart,rend;
10: PetscMPIInt rank;
11: const PetscInt *idx;
12: PetscScalar v;
13: const PetscScalar *values;
15: PetscInitialize(&argc,&args,(char*)0,help);
16: /* Create the matrix for the five point stencil, YET AGAIN */
17: MatCreate(PETSC_COMM_WORLD,&C);
18: MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,m*n,m*n);
19: MatSetFromOptions(C);
20: MatSetUp(C);
21: for (i=0; i<m; i++) {
22: for (j=0; j<n; j++) {
23: v = -1.0; Ii = j + n*i;
24: if (i>0) {J = Ii - n; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
25: if (i<m-1) {J = Ii + n; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
26: if (j>0) {J = Ii - 1; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
27: if (j<n-1) {J = Ii + 1; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
28: v = 4.0; MatSetValues(C,1,&Ii,1,&Ii,&v,INSERT_VALUES);
29: }
30: }
31: MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
32: MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
33: MatView(C,PETSC_VIEWER_STDOUT_WORLD);
35: MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
36: MatGetOwnershipRange(C,&rstart,&rend);
37: for (i=rstart; i<rend; i++) {
38: MatGetRow(C,i,&nz,&idx,&values);
39: if (rank == 0) {
40: for (j=0; j<nz; j++) {
41: PetscPrintf(PETSC_COMM_SELF,"%" PetscInt_FMT " %g ",idx[j],(double)PetscRealPart(values[j]));
42: }
43: PetscPrintf(PETSC_COMM_SELF,"\n");
44: }
45: MatRestoreRow(C,i,&nz,&idx,&values);
46: }
48: MatDestroy(&C);
49: PetscFinalize();
50: return 0;
51: }
53: /*TEST
55: test:
57: TEST*/