// arrayMPI.c
// Run this with 2 processors.  Processor 1 creates an array of 'count' random
// numbers.  In this example 'count' is 100.  Processor 0 (the root process)
// receives this array from processor 1.

// Make sure you are understanding what each parameter in the MPI calls represe\
nt.

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

int main(int argc, char **argv)
{
	int rank, size;
	MPI_Status status;
	double data[100];
	int i, count;
	
	MPI_Init(&argc, &argv);
	MPI_Comm_rank(MPI_COMM_WORLD, &rank); 
	MPI_Comm_size(MPI_COMM_WORLD, &size); 

	count = 100;
	if (rank == 0) {
		MPI_Recv(data, 100, MPI_DOUBLE, 1, 10, MPI_COMM_WORLD, &status);
		printf("Data received from process 1:\n");
		for (i = 0; i < count; i++) { 
			printf("%7.1f", data[i]);
			if (i % 10 == 9) printf("\n");
		}
		printf("\n");
	}
	else {
		if (rank == 1) {
			for (i = 0; i < count; i++)
				data[i] = rand() % 1000;
		MPI_Send(data, count, MPI_DOUBLE, 0, 10, MPI_COMM_WORLD);
		}
	}
    
	MPI_Finalize();
	return 0;
}

/*
CRAY SV1:

cc arrayMPI.c   

mpirun -np 2 a.out

Data received from process 1:
  838.0  758.0  113.0  515.0   51.0  627.0   10.0  419.0  212.0   86.0
  749.0  767.0   84.0   60.0  225.0  543.0   89.0  183.0  137.0  566.0
  966.0  978.0  495.0  311.0  367.0   54.0   31.0  145.0  882.0  736.0
  524.0  505.0  394.0  102.0  851.0   67.0  754.0  653.0  561.0   96.0
  628.0  188.0   85.0  143.0  967.0  406.0  165.0  403.0  562.0  834.0
  353.0  920.0  444.0  803.0  962.0  318.0  422.0  327.0  457.0  945.0
  479.0  983.0  751.0  894.0  670.0  259.0  248.0  757.0  629.0  306.0
  606.0  990.0  738.0  516.0  414.0  262.0  116.0  825.0  181.0  134.0
  343.0   22.0  233.0  536.0  760.0  979.0   71.0  201.0  336.0   61.0
  160.0    5.0  729.0  644.0  475.0  693.0  514.0  139.0   88.0  521.0




*/