! =========================================================================
!  Print name of processor and size of communicator as seen by MPI rank 0
!  Then have every MPI process print its rank (use i3.3 for easy sorting)
!
!    mpif90 -xCORE-AVX512 -O3 mpi_hello.f90 -o mpi_hello
!    mpirun ./mpi_hello | sort
!
!    To run on multiple nodes of a TACC cluster:
!    ibrun ./mpi_hello
! =========================================================================

program mpi_hello
   implicit none
   include 'mpif.h'
   integer :: ierr, nranks, irank, namelen
   character*(MPI_MAX_PROCESSOR_NAME) :: name

   call MPI_Init(ierr)
   call MPI_Comm_size(MPI_COMM_WORLD,   nranks, ierr)
   call MPI_Comm_rank(MPI_COMM_WORLD,    irank, ierr)
   call MPI_Get_processor_name( name,  namelen, ierr)

   if (irank==0) then
      write(*,'("  0> Hello from Xeon SP at processor ",a36)') name
      write(*,'("  0> Size of the MPI communicator is: ", i3)') nranks
   end if

   write(*,'("  => Hello from MPI process ", i3.3)')  irank

   call MPI_Finalize(ierr)

end program mpi_hello