--- /dev/null
+/* Copyright (c) 2013-2014. The SimGrid Team.
+ * All rights reserved. */
+
+/* This program is free software; you can redistribute it and/or modify it
+ * under the terms of the license (GNU LGPL) which comes with this package. */
+
+/*
+ * Test of reduce scatter.
+ *
+ * Each processor contributes its rank + the index to the reduction,
+ * then receives the ith sum
+ *
+ * Can be called with any number of processors.
+ */
+
+#include "mpi.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+int main( int argc, char **argv )
+{
+ int err = 0, toterr;
+ int *sendbuf, *recvbuf, *recvcounts;
+ int size, rank, i, sumval;
+ MPI_Comm comm;
+
+
+ MPI_Init( &argc, &argv );
+ comm = MPI_COMM_WORLD;
+
+ MPI_Comm_size( comm, &size );
+ MPI_Comm_rank( comm, &rank );
+ sendbuf = (int *) malloc( size * sizeof(int) );
+ for (i=0; i<size; i++)
+ sendbuf[i] = rank + i;
+ recvcounts = (int *)malloc( size * sizeof(int) );
+ recvbuf = (int *)malloc( size * sizeof(int) );
+ for (i=0; i<size; i++)
+ recvcounts[i] = 1;
+ MPI_Reduce_scatter( sendbuf, recvbuf, recvcounts, MPI_INT, MPI_SUM, comm );
+ sumval = size * rank + ((size - 1) * size)/2;
+/* recvbuf should be size * (rank + i) */
+ if (recvbuf[0] != sumval) {
+ err++;
+ fprintf( stdout, "Did not get expected value for reduce scatter\n" );
+ fprintf( stdout, "[%d] Got %d expected %d\n", rank, recvbuf[0], sumval );
+ }
+
+ MPI_Allreduce( &err, &toterr, 1, MPI_INT, MPI_SUM, MPI_COMM_WORLD );
+ if (rank == 0 && toterr == 0) {
+ printf( " No Errors\n" );
+ }
+ free(sendbuf);
+ free(recvcounts);
+ free(recvbuf);
+
+ MPI_Finalize( );
+
+ return toterr;
+}