1*c4762a1bSJed Brown /* 2*c4762a1bSJed Brown * 3*c4762a1bSJed Brown * Created on: Sep 25, 2017 4*c4762a1bSJed Brown * Author: Fande Kong 5*c4762a1bSJed Brown */ 6*c4762a1bSJed Brown 7*c4762a1bSJed Brown static char help[] = "Illustrate the use of MatResetPreallocation.\n"; 8*c4762a1bSJed Brown 9*c4762a1bSJed Brown #include "petscmat.h" 10*c4762a1bSJed Brown 11*c4762a1bSJed Brown int main(int argc,char **argv) 12*c4762a1bSJed Brown { 13*c4762a1bSJed Brown Mat A; 14*c4762a1bSJed Brown MPI_Comm comm; 15*c4762a1bSJed Brown PetscInt n=5,m=5,*dnnz,*onnz,i,rstart,rend,M,N; 16*c4762a1bSJed Brown PetscErrorCode ierr; 17*c4762a1bSJed Brown 18*c4762a1bSJed Brown ierr = PetscInitialize(&argc,&argv,0,help);if (ierr) return ierr; 19*c4762a1bSJed Brown comm = MPI_COMM_WORLD; 20*c4762a1bSJed Brown ierr = PetscMalloc2(m,&dnnz,m,&onnz);CHKERRQ(ierr); 21*c4762a1bSJed Brown for (i=0; i<m; i++) { 22*c4762a1bSJed Brown dnnz[i] = 1; 23*c4762a1bSJed Brown onnz[i] = 1; 24*c4762a1bSJed Brown } 25*c4762a1bSJed Brown ierr = MatCreateAIJ(comm,m,n,PETSC_DETERMINE,PETSC_DETERMINE,PETSC_DECIDE,dnnz,PETSC_DECIDE,onnz,&A);CHKERRQ(ierr); 26*c4762a1bSJed Brown ierr = MatSetFromOptions(A);CHKERRQ(ierr); 27*c4762a1bSJed Brown ierr = MatSetUp(A);CHKERRQ(ierr); 28*c4762a1bSJed Brown ierr = PetscFree2(dnnz,onnz);CHKERRQ(ierr); 29*c4762a1bSJed Brown 30*c4762a1bSJed Brown /* This assembly shrinks memory because we do not insert enough number of values */ 31*c4762a1bSJed Brown ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); 32*c4762a1bSJed Brown ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); 33*c4762a1bSJed Brown 34*c4762a1bSJed Brown /* MatResetPreallocation restores the memory required by users */ 35*c4762a1bSJed Brown ierr = MatResetPreallocation(A);CHKERRQ(ierr); 36*c4762a1bSJed Brown ierr = MatSetOption(A,MAT_NEW_NONZERO_ALLOCATION_ERR,PETSC_TRUE);CHKERRQ(ierr); 37*c4762a1bSJed Brown ierr = MatGetOwnershipRange(A,&rstart,&rend);CHKERRQ(ierr); 38*c4762a1bSJed Brown ierr = MatGetSize(A,&M,&N);CHKERRQ(ierr); 39*c4762a1bSJed Brown for (i=rstart; i<rend; i++) { 40*c4762a1bSJed Brown ierr = MatSetValue(A,i,i,2.0,INSERT_VALUES);CHKERRQ(ierr); 41*c4762a1bSJed Brown if (rend<N) { 42*c4762a1bSJed Brown ierr = MatSetValue(A,i,rend,1.0,INSERT_VALUES);CHKERRQ(ierr); 43*c4762a1bSJed Brown } 44*c4762a1bSJed Brown } 45*c4762a1bSJed Brown ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); 46*c4762a1bSJed Brown ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); 47*c4762a1bSJed Brown ierr = MatView(A,PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr); 48*c4762a1bSJed Brown ierr = MatDestroy(&A);CHKERRQ(ierr); 49*c4762a1bSJed Brown ierr = PetscFinalize(); 50*c4762a1bSJed Brown return ierr; 51*c4762a1bSJed Brown } 52*c4762a1bSJed Brown 53*c4762a1bSJed Brown /*TEST 54*c4762a1bSJed Brown 55*c4762a1bSJed Brown test: 56*c4762a1bSJed Brown suffix: 1 57*c4762a1bSJed Brown 58*c4762a1bSJed Brown test: 59*c4762a1bSJed Brown suffix: 2 60*c4762a1bSJed Brown nsize: 2 61*c4762a1bSJed Brown 62*c4762a1bSJed Brown TEST*/ 63