Actual source code: ex36.c

  1: static char help[] = "Parallel vector layout.\n\n";

  3: /*
  4:   Include "petscvec.h" so that we can use vectors.  Note that this file
  5:   automatically includes:
  6:      petscsys.h       - base PETSc routines   petscis.h     - index sets
  7:      petscviewer.h - viewers
  8: */
  9: #include <petscvec.h>

 11: int main(int argc,char **argv)
 12: {
 13:   PetscMPIInt    rank;
 14:   PetscInt       i,istart,iend,n = 6,m,*indices;
 15:   PetscScalar    *values;
 16:   Vec            x;
 17:   PetscBool      set_option_negidx = PETSC_FALSE, set_values_negidx = PETSC_FALSE, get_values_negidx = PETSC_FALSE;

 19:   PetscInitialize(&argc,&argv,(char*)0,help);
 20:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);

 22:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
 23:   PetscOptionsGetBool(NULL,NULL, "-set_option_negidx", &set_option_negidx, NULL);
 24:   PetscOptionsGetBool(NULL,NULL, "-set_values_negidx", &set_values_negidx, NULL);
 25:   PetscOptionsGetBool(NULL,NULL, "-get_values_negidx", &get_values_negidx, NULL);

 27:   VecCreate(PETSC_COMM_WORLD,&x);
 28:   VecSetSizes(x,PETSC_DECIDE,n);
 29:   VecSetFromOptions(x);

 31:   /* If we want to use negative indices, set the option */
 32:   VecSetOption(x, VEC_IGNORE_NEGATIVE_INDICES,set_option_negidx);

 34:   VecGetOwnershipRange(x,&istart,&iend);
 35:   m    = iend - istart;

 37:   PetscMalloc1(n,&values);
 38:   PetscMalloc1(n,&indices);

 40:   for (i=istart; i<iend; i++) {
 41:     values[i - istart] = (rank + 1) * i * 2;
 42:     if (set_values_negidx) indices[i - istart] = (-1 + 2*(i % 2)) * i;
 43:     else                   indices[i - istart] = i;
 44:   }

 46:   PetscSynchronizedPrintf(PETSC_COMM_WORLD, "%d: Setting values...\n", rank);
 47:   for (i = 0; i<m; i++) {
 48:     PetscSynchronizedPrintf(PETSC_COMM_WORLD,"%d: idx[%" PetscInt_FMT "] == %" PetscInt_FMT "; val[%" PetscInt_FMT "] == %f\n",rank,i,indices[i],i,(double)PetscRealPart(values[i]));
 49:   }
 50:   PetscSynchronizedFlush(PETSC_COMM_WORLD,PETSC_STDOUT);

 52:   VecSetValues(x, m, indices, values, INSERT_VALUES);

 54:   /*
 55:      Assemble vector.
 56:   */

 58:   VecAssemblyBegin(x);
 59:   VecAssemblyEnd(x);

 61:   /*
 62:      Extract values from the vector.
 63:   */

 65:   for (i=0; i<m; i++) {
 66:     values[i] = -1.0;
 67:     if (get_values_negidx) indices[i] = (-1 + 2*((istart+i) % 2)) * (istart+i);
 68:     else                   indices[i] = istart+i;
 69:   }

 71:   PetscSynchronizedPrintf(PETSC_COMM_WORLD, "%d: Fetching these values from vector...\n", rank);
 72:   for (i=0; i<m; i++) {
 73:     PetscSynchronizedPrintf(PETSC_COMM_WORLD, "%d: idx[%" PetscInt_FMT "] == %" PetscInt_FMT "\n", rank, i, indices[i]);
 74:   }
 75:   PetscSynchronizedFlush(PETSC_COMM_WORLD,PETSC_STDOUT);

 77:   VecGetValues(x, m, indices, values);

 79:   PetscSynchronizedPrintf(PETSC_COMM_WORLD, "%d: Fetched values:\n", rank);
 80:   for (i = 0; i<m; i++) {
 81:     PetscSynchronizedPrintf(PETSC_COMM_WORLD, "%d: idx[%" PetscInt_FMT "] == %" PetscInt_FMT "; val[%" PetscInt_FMT "] == %f\n",rank,i,indices[i],i,(double)PetscRealPart(values[i]));
 82:   }
 83:   PetscSynchronizedFlush(PETSC_COMM_WORLD,PETSC_STDOUT);

 85:   /*
 86:      Free work space.
 87:   */

 89:   VecDestroy(&x);
 90:   PetscFree(values);
 91:   PetscFree(indices);

 93:   PetscFinalize();
 94:   return 0;
 95: }

 97: /*TEST

 99:    test:
100:       nsize: 2
101:       args: -set_option_negidx -set_values_negidx -get_values_negidx

103: TEST*/