Actual source code: ex5.c
petsc-3.8.4 2018-03-24
2: static char help[] = "Tests binary I/O of vectors and illustrates the use of user-defined event logging.\n\n";
4: #include <petscvec.h>
6: /* Note: Most applications would not read and write a vector within
7: the same program. This example is intended only to demonstrate
8: both input and output. */
10: int main(int argc,char **args)
11: {
13: PetscMPIInt rank,size;
14: PetscInt i,m = 10,low,high,ldim,iglobal;
15: PetscScalar v;
16: Vec u;
17: PetscViewer viewer;
18: #if defined(PETSC_USE_LOG)
19: PetscLogEvent VECTOR_GENERATE,VECTOR_READ;
20: #endif
22: PetscInitialize(&argc,&args,(char*)0,help);if (ierr) return ierr;
23: MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
24: MPI_Comm_size(PETSC_COMM_WORLD,&size);
25: PetscOptionsGetInt(NULL,NULL,"-m",&m,NULL);
27: /* PART 1: Generate vector, then write it in binary format */
29: PetscLogEventRegister("Generate Vector",VEC_CLASSID,&VECTOR_GENERATE);
30: PetscLogEventBegin(VECTOR_GENERATE,0,0,0,0);
31: /* Generate vector */
32: VecCreate(PETSC_COMM_WORLD,&u);
33: VecSetSizes(u,PETSC_DECIDE,m);
34: VecSetFromOptions(u);
35: VecGetOwnershipRange(u,&low,&high);
36: VecGetLocalSize(u,&ldim);
37: for (i=0; i<ldim; i++) {
38: iglobal = i + low;
39: v = (PetscScalar)(i + 100*rank);
40: VecSetValues(u,1,&iglobal,&v,INSERT_VALUES);
41: }
42: VecAssemblyBegin(u);
43: VecAssemblyEnd(u);
44: VecView(u,PETSC_VIEWER_STDOUT_WORLD);
46: PetscPrintf(PETSC_COMM_WORLD,"writing vector in binary to vector.dat ...\n");
47: PetscViewerBinaryOpen(PETSC_COMM_WORLD,"vector.dat",FILE_MODE_WRITE,&viewer);
48: VecView(u,viewer);
49: PetscViewerDestroy(&viewer);
50: VecDestroy(&u);
51: PetscOptionsSetValue(NULL,"-viewer_binary_mpiio","");
53: PetscLogEventEnd(VECTOR_GENERATE,0,0,0,0);
55: /* PART 2: Read in vector in binary format */
57: /* Read new vector in binary format */
58: PetscLogEventRegister("Read Vector",VEC_CLASSID,&VECTOR_READ);
59: PetscLogEventBegin(VECTOR_READ,0,0,0,0);
60: PetscPrintf(PETSC_COMM_WORLD,"reading vector in binary from vector.dat ...\n");
61: PetscViewerBinaryOpen(PETSC_COMM_WORLD,"vector.dat",FILE_MODE_READ,&viewer);
62: VecCreate(PETSC_COMM_WORLD,&u);
63: VecLoad(u,viewer);
64: PetscViewerDestroy(&viewer);
65: PetscLogEventEnd(VECTOR_READ,0,0,0,0);
66: VecView(u,PETSC_VIEWER_STDOUT_WORLD);
68: /* Free data structures */
69: VecDestroy(&u);
70: PetscFinalize();
71: return ierr;
72: }