anchor.diff:                   ierr)
     call MPI_ISend(ab_ptr(myid*offset+1), &
                    offset, &
  -                 MPI_FLOAT, &
  +                 MPI_REAL4, &
                    otherID, &
                    tag, &
                    gcomm, &
  
positive.code: program main
    use mpi
    use occa
    use, intrinsic :: iso_fortran_env, only : stdout=>output_unit, &
                                              stderr=>error_unit
  
negative.code:   call flush(stdout)
    ab_sum = myid
    ab_gather = sum(ab_ptr)
    call MPI_Gather(ab_gather, 1, MPI_REAL4, ab_sum, 1, MPI_REAL4, 0, gcomm, ierr)
    if (myid == 0) then
      if (abs(ab_sum(myid) - ab_sum(otherID)) > 1.0e-8) stop "*** Wrong result ***"
    end if
  