Write an MPI program, count primes which will count the number of prime numbers
ID: 3706841 • Letter: W
Question
Write an MPI program, count primes which will count the number of prime numbers in the numbers from 1 to n inclusive where n is a long integer. The value for n which can be set in the program using a constant should be 50,000.
Each process will test its share of the cases.
Each process should print out any primes that it finds in a readable manner indicating which process found it and the actual prime.
The master process should end with printing a total for the count of the number of primes and the total amount of time taken to find all the primes.
In this program 1 is not a prime number. C Code
Explanation / Answer
EXECUTABLE CODE
#include <math.h>
#include <mpi.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int main(int argc, char *argv[] );
int prime_number (int n, int id, int p);
void timestamp ();
int main (int argc , char *argv[] )
purpose:
main is the main program for PRIME_MPI.
{
int i;
int id;
int ierr;
int n;
int n_factor;
int n_hi;
int n_lo;
int p;
int primes;
int primes_part;
double wtime;
n_lo = 1;
n_hi = 262144;
n_factor = 2;
/*
Initialize MPI.
*/
ierr = MPI_init ( &argc, &argv );
/*
Get the number of proesses.
*/
ierr = MPI_comm_size ( MPI_COMM_WORLD, &p );
/*
determine this processes's rank.
*/
ierr = MPI_COMM_RANK (MPI_COMM_WORLD, &id );
if ( id == 0)
{
timestamp ( );
printf ( " " );
printf ( "PRIME_MPI " );
printf ( " C/MPI version " );
printf ( " " );
printf ( "An MPI example program to count number of primes. " );
printf ( "The numberof processes is %d ", p );
printf ( " " );
printf ( " N pi Time " );
printf ( " " );
}
n = n_lo;
while ( n <= n_hi )
{
if ( id == 0)
{
wtime = MPI_Wtime ( );
}
ierr = MPI_Bcast ( &n, 1, MPI_INT, 0, MPI_COMM_WORLD );
primes_part = prime-number ( n, id, p );
ierr = MPI_Reduce ( &primes_part, &primes, 1, MPI_INT, MPI_SUM, 0, MPI_COMM_WORLD );
if ( id == 0 )
{
wtime = MPI_Wtime ( ) - wtime;
printf ( " %8d %8d %14f ", n, primes, wtime );
}
n = n * n_factor;
}
/*
Terminate MPI.
*/
ierr = MPI_Finalize ( );
/*
Terminate.
*/
if ( id == 0 )
{
printf ( " " );
printf ( "PRIME_MPI - Master process: ");
printf ( " Normal end of execution. ");
timestamp ( );
}
return 0;
}
{
int i;
int j;
int prime;
int total;
total = 0;
for ( i = 2 + id; i <= n; i = i + p )
{
prime = 1;
for ( j = 2; j < i; j ++ )
{
if ( ( i% j ) == 0 )
{
prime = 0;
break;
}
}
total = total + prime;
}
return total;
}
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