1c4762a1bSJed Brown /* 2c4762a1bSJed Brown * 3c4762a1bSJed Brown * Created on: Sep 25, 2017 4c4762a1bSJed Brown * Author: Fande Kong 5c4762a1bSJed Brown */ 6c4762a1bSJed Brown 7c4762a1bSJed Brown static char help[] = "Illustrate the use of MatResetPreallocation.\n"; 8c4762a1bSJed Brown 9c4762a1bSJed Brown #include "petscmat.h" 10c4762a1bSJed Brown 11d71ae5a4SJacob Faibussowitsch int main(int argc, char **argv) 12d71ae5a4SJacob Faibussowitsch { 13c4762a1bSJed Brown Mat A; 14c4762a1bSJed Brown MPI_Comm comm; 15c4762a1bSJed Brown PetscInt n = 5, m = 5, *dnnz, *onnz, i, rstart, rend, M, N; 16c4762a1bSJed Brown 17327415f7SBarry Smith PetscFunctionBeginUser; 189566063dSJacob Faibussowitsch PetscCall(PetscInitialize(&argc, &argv, 0, help)); 19c4762a1bSJed Brown comm = MPI_COMM_WORLD; 209566063dSJacob Faibussowitsch PetscCall(PetscMalloc2(m, &dnnz, m, &onnz)); 21c4762a1bSJed Brown for (i = 0; i < m; i++) { 22c4762a1bSJed Brown dnnz[i] = 1; 23c4762a1bSJed Brown onnz[i] = 1; 24c4762a1bSJed Brown } 259566063dSJacob Faibussowitsch PetscCall(MatCreateAIJ(comm, m, n, PETSC_DETERMINE, PETSC_DETERMINE, PETSC_DECIDE, dnnz, PETSC_DECIDE, onnz, &A)); 269566063dSJacob Faibussowitsch PetscCall(MatSetFromOptions(A)); 279566063dSJacob Faibussowitsch PetscCall(MatSetUp(A)); 289566063dSJacob Faibussowitsch PetscCall(PetscFree2(dnnz, onnz)); 29c4762a1bSJed Brown 30*1f14be2bSBarry Smith /* since the matrix has never been assembled this reset should do nothing */ 31*1f14be2bSBarry Smith PetscCall(MatResetPreallocation(A)); 32*1f14be2bSBarry Smith 33c4762a1bSJed Brown /* This assembly shrinks memory because we do not insert enough number of values */ 349566063dSJacob Faibussowitsch PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY)); 359566063dSJacob Faibussowitsch PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY)); 36c4762a1bSJed Brown 37*1f14be2bSBarry Smith /* MatResetPreallocation() restores the memory required by users */ 389566063dSJacob Faibussowitsch PetscCall(MatResetPreallocation(A)); 399566063dSJacob Faibussowitsch PetscCall(MatSetOption(A, MAT_NEW_NONZERO_ALLOCATION_ERR, PETSC_TRUE)); 409566063dSJacob Faibussowitsch PetscCall(MatGetOwnershipRange(A, &rstart, &rend)); 419566063dSJacob Faibussowitsch PetscCall(MatGetSize(A, &M, &N)); 42c4762a1bSJed Brown for (i = rstart; i < rend; i++) { 439566063dSJacob Faibussowitsch PetscCall(MatSetValue(A, i, i, 2.0, INSERT_VALUES)); 4448a46eb9SPierre Jolivet if (rend < N) PetscCall(MatSetValue(A, i, rend, 1.0, INSERT_VALUES)); 45c4762a1bSJed Brown } 469566063dSJacob Faibussowitsch PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY)); 479566063dSJacob Faibussowitsch PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY)); 489566063dSJacob Faibussowitsch PetscCall(MatView(A, PETSC_VIEWER_STDOUT_WORLD)); 499566063dSJacob Faibussowitsch PetscCall(MatDestroy(&A)); 509566063dSJacob Faibussowitsch PetscCall(PetscFinalize()); 51b122ec5aSJacob Faibussowitsch return 0; 52c4762a1bSJed Brown } 53c4762a1bSJed Brown 54c4762a1bSJed Brown /*TEST 55c4762a1bSJed Brown 56c4762a1bSJed Brown test: 57c4762a1bSJed Brown suffix: 1 58c4762a1bSJed Brown 59c4762a1bSJed Brown test: 60c4762a1bSJed Brown suffix: 2 61c4762a1bSJed Brown nsize: 2 62c4762a1bSJed Brown 63c4762a1bSJed Brown TEST*/ 64