MPI/C – Oddly [or Evenly] Saying ello!

/* hello_world_oddeven.c
 * PARALLEL [MPI] C PROGRAM TO PRINT 'HELLO, WORLD!' TO THE SCREEN AS
 * WELL AS WHETHER THE PROCESSOR ID IS EITHER ODD OR EVEN.
 *
 * TESTED SUCCESSFULLY WITH MPICH2 (1.3.1) COMPILED AGAINST GCC (4.1.2) 
 * IN A LINUX BOX WITH QUAD CORE INTEL XEON PROCESSOR (1.86 GHz) & 4GB OF RAM.
 *
 * FIRST WRITTEN: GOWTHAM; Sat, 27 Nov 2010 10:30:11 -0500
 * LAST MODIFIED: GOWTHAM; Sat, 27 Nov 2010 11:25:34 -0500
 *
 * URL:
 * http://sgowtham.net/blog/2010/11/28/mpi-c-oddly-or-evenly-saying-ello/
 *
 * COMPILATION:
 * mpicc -g -Wall hello_world_oddeven.c -o hello_world_oddeven.x
 *
 * EXECUTION:
 * mpirun -machinefile MACHINEFILE -np NPROC ./hello_world_oddeven.x
 *
 * NPROC       : NUMBER OF PROCESSORS ALLOCATED TO RUNNING THIS PROGRAM
 * MACHINEFILE : FILE LISTING THE HOSTNAMES OF PROCESSORS ALLOCATED TO
 *               RUNNING THIS PROGRAM
 *
*/
 
/* STANDARD HEADERS AND DEFINITIONS 
 * REFERENCE: http://en.wikipedia.org/wiki/C_standard_library
*/
#include <stdio.h>  /* Core input/output operations                         */
#include <stdlib.h> /* Conversions, random numbers, memory allocation, etc. */
#include <math.h>   /* Common mathematical functions                        */
#include <time.h>   /* Converting between various date/time formats         */
#include <mpi.h>    /* MPI functionality                                    */
 
/* MAIN PROGRAM BEGINS */
int main(int argc, char **argv) {
 
  /* VARIABLE DECLARATION */
  int proc_id,       /* Process identifier   */
      n_procs;       /* Number of processors */
 
  /* INITIALIZE MPI */
  MPI_Init(&argc, &argv);
 
  /* GET THE PROCESS ID AND NUMBER OF PROCESSORS */
  MPI_Comm_rank(MPI_COMM_WORLD, &proc_id);
  MPI_Comm_size(MPI_COMM_WORLD, &n_procs);
 
  /* PRINT 'HELLO, WORLD!' FROM EVERY PROCESSOR 
   * ALSO INDICATE WHETHER THE PROCESSOR ID IS ODD OR EVEN
  */
  if (proc_id % 2 == 0) {
    printf("Hello, World! From %d [e] out of %d processors\n", proc_id, n_procs);
  } else {
    printf("Hello, World! From %d [o] out of %d processors\n", proc_id, n_procs);
  }
 
  /* FINALIZE MPI */
  MPI_Finalize();
 
  /* INDICATE THE TERMINATION OF THE PROGRAM */
  return 0;
 
} /* MAIN PROGRAM ENDS */