1c4762a1bSJed Brown /* 2*46233b44SBarry Smith Contributed by: Fande Kong 3c4762a1bSJed Brown */ 4c4762a1bSJed Brown 5c4762a1bSJed Brown static char help[] = "Illustrate the use of MatResetPreallocation.\n"; 6c4762a1bSJed Brown 7*46233b44SBarry Smith #include <petscmat.h> 8c4762a1bSJed Brown 9d71ae5a4SJacob Faibussowitsch int main(int argc, char **argv) 10d71ae5a4SJacob Faibussowitsch { 11c4762a1bSJed Brown Mat A; 12c4762a1bSJed Brown MPI_Comm comm; 13c4762a1bSJed Brown PetscInt n = 5, m = 5, *dnnz, *onnz, i, rstart, rend, M, N; 14c4762a1bSJed Brown 15327415f7SBarry Smith PetscFunctionBeginUser; 169566063dSJacob Faibussowitsch PetscCall(PetscInitialize(&argc, &argv, 0, help)); 17c4762a1bSJed Brown comm = MPI_COMM_WORLD; 189566063dSJacob Faibussowitsch PetscCall(PetscMalloc2(m, &dnnz, m, &onnz)); 19c4762a1bSJed Brown for (i = 0; i < m; i++) { 20c4762a1bSJed Brown dnnz[i] = 1; 21c4762a1bSJed Brown onnz[i] = 1; 22c4762a1bSJed Brown } 239566063dSJacob Faibussowitsch PetscCall(MatCreateAIJ(comm, m, n, PETSC_DETERMINE, PETSC_DETERMINE, PETSC_DECIDE, dnnz, PETSC_DECIDE, onnz, &A)); 249566063dSJacob Faibussowitsch PetscCall(MatSetFromOptions(A)); 259566063dSJacob Faibussowitsch PetscCall(MatSetUp(A)); 269566063dSJacob Faibussowitsch PetscCall(PetscFree2(dnnz, onnz)); 27c4762a1bSJed Brown 281f14be2bSBarry Smith /* since the matrix has never been assembled this reset should do nothing */ 291f14be2bSBarry Smith PetscCall(MatResetPreallocation(A)); 301f14be2bSBarry Smith 31c4762a1bSJed Brown /* This assembly shrinks memory because we do not insert enough number of values */ 329566063dSJacob Faibussowitsch PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY)); 339566063dSJacob Faibussowitsch PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY)); 34c4762a1bSJed Brown 351f14be2bSBarry Smith /* MatResetPreallocation() restores the memory required by users */ 369566063dSJacob Faibussowitsch PetscCall(MatResetPreallocation(A)); 379566063dSJacob Faibussowitsch PetscCall(MatSetOption(A, MAT_NEW_NONZERO_ALLOCATION_ERR, PETSC_TRUE)); 389566063dSJacob Faibussowitsch PetscCall(MatGetOwnershipRange(A, &rstart, &rend)); 399566063dSJacob Faibussowitsch PetscCall(MatGetSize(A, &M, &N)); 40c4762a1bSJed Brown for (i = rstart; i < rend; i++) { 419566063dSJacob Faibussowitsch PetscCall(MatSetValue(A, i, i, 2.0, INSERT_VALUES)); 4248a46eb9SPierre Jolivet if (rend < N) PetscCall(MatSetValue(A, i, rend, 1.0, INSERT_VALUES)); 43c4762a1bSJed Brown } 449566063dSJacob Faibussowitsch PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY)); 459566063dSJacob Faibussowitsch PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY)); 469566063dSJacob Faibussowitsch PetscCall(MatView(A, PETSC_VIEWER_STDOUT_WORLD)); 479566063dSJacob Faibussowitsch PetscCall(MatDestroy(&A)); 489566063dSJacob Faibussowitsch PetscCall(PetscFinalize()); 49b122ec5aSJacob Faibussowitsch return 0; 50c4762a1bSJed Brown } 51c4762a1bSJed Brown 52c4762a1bSJed Brown /*TEST 53c4762a1bSJed Brown 54c4762a1bSJed Brown test: 55c4762a1bSJed Brown suffix: 1 56c4762a1bSJed Brown 57c4762a1bSJed Brown test: 58c4762a1bSJed Brown suffix: 2 59c4762a1bSJed Brown nsize: 2 60c4762a1bSJed Brown 61c4762a1bSJed Brown TEST*/ 62