MPI_REDUCE error

Question

I dont understand why the following program is not working. When I am running it with "mpirun -np 2 a.out" I would expect it to print "N: 2" but instead it is giving me a seg fault.

Thank you

main.f

  program main

  implicit none

  include 'mpif.h'

  integer me, ngs,ierror

  call  inimpi(me, ngs)

  call calc

  call mpi_finalize( ierror )

  stop
  end

inimpi.f

  subroutine  inimpi(me, ngs)

  include  'mpif.h'

  integer me, ngs, ierror

  call  mpi_init( ierror )
  call  mpi_comm_rank( mpi_comm_world, me,  ierror )
  call  mpi_comm_size( mpi_comm_world, ngs, ierror )

  return
  end

calc.f

  subroutine  calc

  include 'mpif.h'

  integer  p, e, ierror

  p = 1

  call mpi_reduce(p, e, 1, mpi_integer,
 &     mpi_sum, mpi_comm_world, ierror)

  print *, "N: ", e
  return
  end

none_00 · Accepted Answer · 2013-03-16 11:08:34Z

3

Taken from the mpich2 documentation:

int MPI_Reduce(void *sendbuf, void *recvbuf, int count, MPI_Datatype datatype, 
               MPI_Op op, int root, MPI_Comm comm)

You didn't specify the root for mpi_reduce. Because of this, mpi_comm_world is used as root and ierror is used as MPI_Comm. Did you mean to use MPI_Allreduce, which doesn't need a root argument?

Oh, and try to use use mpi instead of include 'mpif.h' if possible, this might have even caught the current error.

answered Mar 16, 2013 at 11:08

none_00

1965 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

MPI_REDUCE error

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related