1 2 static char help[] = "Tests MatCreateSubMatrices().\n\n"; 3 4 #include <petscmat.h> 5 6 int main(int argc,char **args) 7 { 8 Mat A,B,*Bsub; 9 PetscInt i,j,m = 6,n = 6,N = 36,Ii,J; 10 PetscScalar v; 11 IS isrow; 12 13 PetscCall(PetscInitialize(&argc,&args,(char*)0,help)); 14 PetscCall(MatCreateSeqAIJ(PETSC_COMM_WORLD,N,N,5,NULL,&A)); 15 for (i=0; i<m; i++) { 16 for (j=0; j<n; j++) { 17 v = -1.0; Ii = j + n*i; 18 if (i>0) {J = Ii - n; PetscCall(MatSetValues(A,1,&Ii,1,&J,&v,INSERT_VALUES));} 19 if (i<m-1) {J = Ii + n; PetscCall(MatSetValues(A,1,&Ii,1,&J,&v,INSERT_VALUES));} 20 if (j>0) {J = Ii - 1; PetscCall(MatSetValues(A,1,&Ii,1,&J,&v,INSERT_VALUES));} 21 if (j<n-1) {J = Ii + 1; PetscCall(MatSetValues(A,1,&Ii,1,&J,&v,INSERT_VALUES));} 22 v = 4.0; PetscCall(MatSetValues(A,1,&Ii,1,&Ii,&v,INSERT_VALUES)); 23 } 24 } 25 PetscCall(MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY)); 26 PetscCall(MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY)); 27 PetscCall(MatView(A,PETSC_VIEWER_STDOUT_SELF)); 28 29 /* take the first diagonal block */ 30 PetscCall(ISCreateStride(PETSC_COMM_WORLD,m,0,1,&isrow)); 31 PetscCall(MatCreateSubMatrices(A,1,&isrow,&isrow,MAT_INITIAL_MATRIX,&Bsub)); 32 B = *Bsub; 33 PetscCall(ISDestroy(&isrow)); 34 PetscCall(MatView(B,PETSC_VIEWER_STDOUT_SELF)); 35 PetscCall(MatDestroySubMatrices(1,&Bsub)); 36 37 /* take a strided block */ 38 PetscCall(ISCreateStride(PETSC_COMM_WORLD,m,0,2,&isrow)); 39 PetscCall(MatCreateSubMatrices(A,1,&isrow,&isrow,MAT_INITIAL_MATRIX,&Bsub)); 40 B = *Bsub; 41 PetscCall(ISDestroy(&isrow)); 42 PetscCall(MatView(B,PETSC_VIEWER_STDOUT_SELF)); 43 PetscCall(MatDestroySubMatrices(1,&Bsub)); 44 45 /* take the last block */ 46 PetscCall(ISCreateStride(PETSC_COMM_WORLD,m,N-m-1,1,&isrow)); 47 PetscCall(MatCreateSubMatrices(A,1,&isrow,&isrow,MAT_INITIAL_MATRIX,&Bsub)); 48 B = *Bsub; 49 PetscCall(ISDestroy(&isrow)); 50 PetscCall(MatView(B,PETSC_VIEWER_STDOUT_SELF)); 51 52 PetscCall(MatDestroySubMatrices(1,&Bsub)); 53 PetscCall(MatDestroy(&A)); 54 55 PetscCall(PetscFinalize()); 56 return 0; 57 } 58 59 /*TEST 60 61 test: 62 63 TEST*/ 64