Actual source code: ex5.c

  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. */

 12: int main(int argc,char **args)
 13: {
 15:   PetscMPIInt    rank,size;
 16:   PetscInt       i,m = 10,low,high,ldim,iglobal;
 17:   PetscScalar    v;
 18:   Vec            u;
 19:   PetscViewer    viewer;
 20:   PetscEvent     VECTOR_GENERATE,VECTOR_READ;

 22:   PetscInitialize(&argc,&args,(char *)0,help);
 23:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
 24:   MPI_Comm_size(PETSC_COMM_WORLD,&size);
 25:   PetscOptionsGetInt(PETSC_NULL,"-m",&m,PETSC_NULL);

 27:   /* PART 1:  Generate vector, then write it in binary format */

 29:   PetscLogEventRegister(&VECTOR_GENERATE,"Generate Vector",VEC_COOKIE);
 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");

 48:   PetscViewerBinaryOpen(PETSC_COMM_WORLD,"vector.dat",PETSC_FILE_CREATE,&viewer);
 49:   VecView(u,viewer);
 50:   PetscViewerDestroy(viewer);
 51:   VecDestroy(u);
 52:   PetscLogEventEnd(VECTOR_GENERATE,0,0,0,0);

 54:   /* PART 2:  Read in vector in binary format */

 56:   /* All processors wait until test vector has been dumped */
 57:   MPI_Barrier(PETSC_COMM_WORLD);
 58:   PetscSleep(10);

 60:   /* Read new vector in binary format */
 61:   PetscLogEventRegister(&VECTOR_READ,"Read Vector",VEC_COOKIE);
 62:   PetscLogEventBegin(VECTOR_READ,0,0,0,0);
 63:   PetscPrintf(PETSC_COMM_WORLD,"reading vector in binary from vector.dat ...\n");
 64:   PetscViewerBinaryOpen(PETSC_COMM_WORLD,"vector.dat",PETSC_FILE_RDONLY,&viewer);
 65:   VecLoad(viewer,PETSC_NULL,&u);
 66:   PetscViewerDestroy(viewer);
 67:   PetscLogEventEnd(VECTOR_READ,0,0,0,0);
 68:   VecView(u,PETSC_VIEWER_STDOUT_WORLD);

 70:   /* Free data structures */
 71:   VecDestroy(u);
 72:   PetscFinalize();
 73:   return 0;
 74: }