Dr. David Cronk Innovative Computing Lab University of ... - It works!

Create a non-commutative sum
Void my_add (void *in, void *out, int *len, MPI_Datatype *dtype)
{
int i;
int *iarray1, *iarray2;
float *farray1, *farray2;
if (*dtype == MPI_INT) {
iarray1 = in; iarray2 = out;
for (i = 0; i < *len; i++)
iarray2[i] = iarra2[i] + iarray1[i];
} else {
farray1 = in; farray2 = out;
for (i = 0; i < *len; i++)
iarray2[i] = iarra2[i] + iarray1[i];
}
}
…
MPI_Op myop;
MPI_Op_create ((MPI_User_function*)my_add, False, &myop);
MPI_Reduce (inbuf, outbuf, num, MPI_FLOAT, myop, 0, MPI_COMM_WORLD);
David Cronk 122