MPI_Gather gives seg fault in the most basic code

Question

I am working on a much bigger program where I struggle with MPI_Gather.

I wrote a minimal example code, see below.

 program test
  use MPI
  integer          


        

Answer 1

You have forgotten to add the return error code to the call to MPI_Gather as the last argument. The value of the return code is being written to an unmapped address.

It should read

call MPI_Gather(send, 1, MPI_DOUBLE_PRECISION, &
                recv, 1, MPI_DOUBLE_PRECISION, 0, MPI_COMM_WORLD, ierr)

ifort catches this at the compilation stage. It looks like your compiler (gfortran?) doesn't