====== Installation of MPI on Linux ======

There are 2 main implementations of MPI MPICH and Open MPI.\\
Below is the installation for open MPI.\\
For mpich See this [[https://www.mpich.org/static/downloads/3.2/mpich-3.2-installguide.pdf|link]].


===== Installation =====
Type in a terminal:
<box round>
''sudo apt-get install libopenmpi-dev openmpi-bin''
</box>

===== Small test =====

Download the file below.

<code fortran hello_world.f90>
!  Fortran example  
   program hello
   include 'mpif.h'
   integer rank, size, ierror, tag, status(MPI_STATUS_SIZE)
   
   call MPI_INIT(ierror)
   call MPI_COMM_SIZE(MPI_COMM_WORLD, size, ierror)
   call MPI_COMM_RANK(MPI_COMM_WORLD, rank, ierror)
   print*, 'node', rank, ': Hello world'
   call MPI_FINALIZE(ierror)
   end
</code>

Type in a terminal:
<box round>
''mpif90 hello_world.f90 -o hello_world''\\
''mpiexec -n 4 ./hello_world''
</box>
It should display:
<code>
 node           0 : Hello world
 node           1 : Hello world
 node           2 : Hello world
 node           3 : Hello world
</code>