1 2 static char help[] = "Tests reordering a matrix.\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 = 5,Ii,J; 10 PetscScalar v; 11 IS perm,iperm; 12 13 PetscCall(PetscInitialize(&argc,&args,(char*)0,help)); 14 PetscCall(MatCreate(PETSC_COMM_SELF,&C)); 15 PetscCall(MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,m*n,m*n)); 16 PetscCall(MatSetFromOptions(C)); 17 PetscCall(MatSetUp(C)); 18 19 /* create the matrix for the five point stencil, YET AGAIN*/ 20 for (i=0; i<m; i++) { 21 for (j=0; j<n; j++) { 22 v = -1.0; Ii = j + n*i; 23 if (i>0) {J = Ii - n; PetscCall(MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES));} 24 if (i<m-1) {J = Ii + n; PetscCall(MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES));} 25 if (j>0) {J = Ii - 1; PetscCall(MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES));} 26 if (j<n-1) {J = Ii + 1; PetscCall(MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES));} 27 v = 4.0; PetscCall(MatSetValues(C,1,&Ii,1,&Ii,&v,INSERT_VALUES)); 28 } 29 } 30 PetscCall(MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY)); 31 PetscCall(MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY)); 32 33 PetscCall(MatGetOrdering(C,MATORDERINGND,&perm,&iperm)); 34 PetscCall(ISView(perm,PETSC_VIEWER_STDOUT_SELF)); 35 PetscCall(ISView(iperm,PETSC_VIEWER_STDOUT_SELF)); 36 PetscCall(MatView(C,PETSC_VIEWER_STDOUT_SELF)); 37 38 PetscCall(ISDestroy(&perm)); 39 PetscCall(ISDestroy(&iperm)); 40 PetscCall(MatDestroy(&C)); 41 PetscCall(PetscFinalize()); 42 return 0; 43 } 44 45 /*TEST 46 47 test: 48 49 TEST*/ 50