#include <stdio.h>
#include <mpi.h>

int main(int argc, char **argv )
 {
  int i;
  int sum;
  int a[100],b[100],c[100];
  int myid, numprocs;
  double precision;
  double start, end;
  char sig[80];
  MPI_Status status;

  MPI_Init(&argc, &argv);
  MPI_Comm_size(MPI_COMM_WORLD, &numprocs);
  MPI_Comm_rank(MPI_COMM_WORLD, &myid); 
  for (i=0; i<argc; i++) printf("argv[%d]=%s\n",i,argv[i]);
  if (myid == 0)
   {
    printf("Hello from id %d, %d of %d processes\n",myid,myid+1,numprocs);
    for(i=1; i<numprocs; i++)
     {
      MPI_Recv(sig,sizeof(sig),MPI_CHAR,i,0,MPI_COMM_WORLD,&status);
      printf("%s",sig);
      printf("Message source = %d\n",status.MPI_SOURCE);
      printf("Message tag = %d\n",status.MPI_TAG);
      printf("Message Error condition = %d\n",status.MPI_ERROR);
     }
    start = MPI_Wtime();
    for (i=0; i<100; i++) 
     {
      a[i] = i;
      b[i] = i * 10;
      c[i] = i + 7;
      a[i] = b[i] * c[i];
     }
    end = MPI_Wtime();
    printf("Our timers precision is %.20f seconds\n",MPI_Wtick());
    printf("This silly loop took %.5f seconds\n",end-start);
   }
  else 
   {
    sprintf(sig,"Hello from id %d, %d of %d processes\n",myid,myid+1,numprocs);
    MPI_Send(sig,sizeof(sig),MPI_CHAR,0,0,MPI_COMM_WORLD);
   }
  MPI_Allreduce(&myid,&sum,1,MPI_INT,MPI_SUM,MPI_COMM_WORLD);
  printf("Sum of all process ids = %d\n",sum);
  MPI_Finalize();
  return 0;
 }