text: /* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
  /*
   *  (C) 2001 by Argonne National Laboratory.
   *      See COPYRIGHT in top-level directory.
   */
  #include "mpi.h"
  #include <stdio.h>
  #include "mpitest.h"
  
  void addem(int *, int *, int *, MPI_Datatype *);
  void assoc(int *, int *, int *, MPI_Datatype *);
  
  void addem(int *invec, int *inoutvec, int *len, MPI_Datatype * dtype)
  {
      int i;
      for (i = 0; i < *len; i++)
          inoutvec[i] += invec[i];
  }
  
  #define BAD_ANSWER 100000
  
  /*
      The operation is inoutvec[i] = invec[i] op inoutvec[i]
      (see 4.9.4).  The order is important.
  
      Note that the computation is in process rank (in the communicator)
      order, independant of the root.
   */
  void assoc(int *invec, int *inoutvec, int *len, MPI_Datatype * dtype)
  {
      int i;
      for (i = 0; i < *len; i++) {
          if (inoutvec[i] <= invec[i]) {
              int rank;
              MPI_Comm_rank(MPI_COMM_WORLD, &rank);
              fprintf(stderr, "[%d] inout[0] = %d, in[0] = %d\n", rank, inoutvec[0], invec[0]);
              inoutvec[i] = BAD_ANSWER;
          }
          else
              inoutvec[i] = invec[i];
      }
  }
  
  int main(int argc, char **argv)
  {
      int rank, size, i;
      int data;
      int errors = 0;
      int result = -100;
      int correct_result;
      MPI_Op op_assoc, op_addem;
  
      MTest_Init(&argc, &argv);
      MPI_Comm_rank(MPI_COMM_WORLD, &rank);
      MPI_Comm_size(MPI_COMM_WORLD, &size);
  
      data = rank;
  
      correct_result = 0;
      for (i = 0; i <= rank; i++)
          correct_result += i;
  
      MPI_Scan(&data, &result, 1, MPI_INT, MPI_SUM, MPI_COMM_WORLD);
      if (result != correct_result) {
          fprintf(stderr, "[%d] Error suming ints with scan\n", rank);
          errors++;
      }
  
      MPI_Scan(&data, &result, 1, MPI_INT, MPI_SUM, MPI_COMM_WORLD);
      if (result != correct_result) {
          fprintf(stderr, "[%d] Error summing ints with scan (2)\n", rank);
          errors++;
      }
  
      data = rank;
      result = -100;
      MPI_Op_create((MPI_User_function *) assoc, 0, &op_assoc);
      MPI_Op_create((MPI_User_function *) addem, 1, &op_addem);
      MPI_Scan(&data, &result, 1, MPI_INT, op_addem, MPI_COMM_WORLD);
      if (result != correct_result) {
          fprintf(stderr, "[%d] Error summing ints with scan (userop)\n", rank);
          errors++;
      }
  
      MPI_Scan(&data, &result, 1, MPI_INT, op_addem, MPI_COMM_WORLD);
      if (result != correct_result) {
          fprintf(stderr, "[%d] Error summing ints with scan (userop2)\n", rank);
          errors++;
      }
      result = -100;
      data = rank;
      MPI_Scan(&data, &result, 1, MPI_INT, op_assoc, MPI_COMM_WORLD);
      if (result == BAD_ANSWER) {
          fprintf(stderr, "[%d] Error scanning with non-commutative op\n", rank);
          errors++;
      }
  
      MPI_Op_free(&op_assoc);
      MPI_Op_free(&op_addem);
  
      MTest_Finalize(errors);
      MPI_Finalize();
      return MTestReturnValue(errors);
  }
  