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. */

 10: int main(int argc, char **args)
 11: {
 12:   PetscMPIInt rank, size;
 13:   PetscInt    i, m = 10, low, high, ldim, iglobal;
 14:   PetscScalar v;
 15:   Vec         u;
 16:   PetscViewer viewer;
 17: #if defined(PETSC_USE_LOG)
 18:   PetscLogEvent VECTOR_GENERATE, VECTOR_READ;
 19: #endif

 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(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 0;
 72: }

 74: /*TEST

 76:      test:
 77:        nsize: 1
 78:        requires: mpiio

 80:      test:
 81:        suffix: 2
 82:        nsize: 2
 83:        requires: mpiio

 85: TEST*/