text: /* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
  /*
   *
   *  (C) 2003 by Argonne National Laboratory.
   *      See COPYRIGHT in top-level directory.
   */
  
  #include "mpi.h"
  #include "mpitest.h"
  #include <stdlib.h>
  #include <stdio.h>
  
  /* Gather data from a vector to contiguous.  Use IN_PLACE */
  
  int main( int argc, char **argv )
  {
      double *vecout;
      MPI_Comm comm;
      int    count, minsize = 2;
      int    i, errs = 0;
      int    rank, size;
  
      MTest_Init( &argc, &argv );
  
      while (MTestGetIntracommGeneral( &comm, minsize, 1 )) {
  	if (comm == MPI_COMM_NULL) continue;
  	/* Determine the sender and receiver */
  	MPI_Comm_rank( comm, &rank );
  	MPI_Comm_size( comm, &size );
  	
          for (count = 1; count < 9000; count = count * 2) {
              vecout = (double *)malloc( size * count * sizeof(double) );
              
              for (i=0; i<count; i++) {
                  vecout[rank*count+i] = rank*count+i;
              }
              MPI_Allgather( MPI_IN_PLACE, -1, MPI_DATATYPE_NULL, 
                             vecout, count, MPI_DOUBLE, comm );
              for (i=0; i<count*size; i++) {
                  if (vecout[i] != i) {
                      errs++;
                      if (errs < 10) {
                          fprintf( stderr, "vecout[%d]=%d\n",
                                   i, (int)vecout[i] );
                      }
                  }
              }
              free( vecout );
          }
  
  	MTestFreeComm( &comm );
      }
  
  #if MTEST_HAVE_MIN_MPI_VERSION(2,2)
      MPI_Comm_set_errhandler(MPI_COMM_WORLD, MPI_ERRORS_RETURN);
      MPI_Comm_rank(MPI_COMM_WORLD, &rank);
      MPI_Comm_size(MPI_COMM_WORLD, &size);
      vecout = (double *) malloc(size * sizeof(double));
      if (MPI_SUCCESS == MPI_Allgather(&vecout[rank], 1, MPI_DOUBLE,
                                        vecout, 1, MPI_DOUBLE, MPI_COMM_WORLD))
          errs++;
      free(vecout);
  #endif
  
      MTest_Finalize( errs );
      MPI_Finalize();
      return 0;
  }
  
  
  