Dear All, I'm running a complex program with a number of MPI_REDUCE calls, every call uses MPI_IN_PLACE as the first parameter (the send buffer).
I'm currently testing this program on Mac 10.6 with macports installed. Unfortunately all MPI_REDUCE calls with MPI_IN_PLACE, seem to fail. I've pinpointed the problem to the MPI_IN_PLACE parameter location, it seems to matter if it is the first or the second parameter to the MPI_REDUCE call. This is specific for fortran, in C the sequence does not matter! A simple program to test this: PROGRAM MAIN implicit none include 'mpif.h' integer :: x(10) integer :: provided,ioerror call MPI_INIT(ioerror) x = 1 print *, x call MPI_REDUCE(x, MPI_IN_PLACE,10, MPI_INTEGER, MPI_SUM, 0,MPI_COMM_WORLD, ioerror) print *, x call MPI_REDUCE(MPI_IN_PLACE, x,10, MPI_INTEGER, MPI_SUM, 0,MPI_COMM_WORLD, ioerror) print *, x call MPI_FINALIZE(ioerror) END PROGRAM I run this on one process (mpiexec ./a.out) I'm running with openmpi version 1.5.4 (macports) The openmpi is compiled with gfortran 4.4.6 Is this a bug in openmpi or is my understanding of MPI_REDUCE wrong? Best regards, Arjen
