public reduce_scatter(String[] args) throws Exception {
final int MAXLEN = 10000;
int out[] = new int[MAXLEN * 100];
int in[] = new int[MAXLEN * 100];
int i, j, k;
int myself, tasks;
int recvcounts[] = new int[128];
MPI.Init(args);
myself = MPI.COMM_WORLD.Rank();
tasks = MPI.COMM_WORLD.Size();
if (tasks > 8) {
if (myself == 0) {
System.out.println("reduce_scatter must run with 8 tasks!");
}
MPI.Finalize();
return;
}
j = 10;
// for(j=1;j<=MAXLEN*tasks;j*=10) {
for (i = 0; i < tasks; i++) recvcounts[i] = j;
for (i = 0; i < j * tasks; i++) out[i] = i;
MPI.COMM_WORLD.Reduce_scatter(out, 0, in, 0, recvcounts, MPI.INT, MPI.SUM);
for (k = 0; k < j; k++) {
if (in[k] != tasks * (myself * j + k)) {
System.out.println(
"bad answer ("
+ in[k]
+ ") at index "
+ k
+ " of "
+ j
+ "(should be "
+ tasks * (myself * j + k)
+ ")");
break;
}
}
// }
MPI.COMM_WORLD.Barrier();
if (myself == 0) System.out.println("Reduce_scatter TEST COMPLETE");
MPI.Finalize();
}
