0

I have a program that gives me estimation of pi, and time elapsed depends on my input numbers.

Can someone please tell me how to compile this? I have the code but it's mystery how to compile and r

un it...

```
* Compiler:
* mpicc -g -Wall -o name name.c
* mpirun -np 4 name
*******************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <math.h>
#include <mpi.h>
#define M 0
#define PI 3.14159265
double RandomN (double a, double b) // Random Number Generator
{
double r;
r = ((b-a) * ((double) rand() / (double) RAND_MAX)) + a;
return r;
}
/* Main */
int main(int argc, char*argv[])
{
long long int *n_throw=0; // Number of darts thrown
int p_rnk, // Processor rank
p_sz, // Number of processors
NC, // Number in circle
i, // Toss
llimit, // Lower limit for random numbers
ulimit; // Upper limit for random numbers
double pi_estimate, // Estimation of PI
pi_sum, // Sum of PI values from each WORKER
x, // x coordinate, between -1 & +1
y, // y coordinate, between -1 & +1
z, // Sum of x^2 and y^2 (Distance Squared)
start_time, // Wall clock - Start time
end_time; // Wall clock - End time
struct timeval stime;
NC =0; // Number of darts that hit the circle = 0 (Initially)
llimit = -1; // Lower limit for random numbers = -1
ulimit = 1; // Upper limit for random numbers = 1
MPI_Init(&argc, &argv); // START MPI
MPI_Comm_rank (MPI_COMM_WORLD, &p_rnk); // Find the rank of the process
MPI_Comm_size (MPI_COMM_WORLD, &p_sz); // Find the size of the process
if (p_rnk == M){ // If using Master process then:
printf ("\nHello MPI World\n\n");
printf("Number of Darts: \n"); // cout << Number of Darts:
scanf("%lld",n_throw); // cin >> n_throw
printf(" Number of processes: %d \n", p_sz); // cout << Number of processes: p_sz
printf(" Number of darts: %Ld \n", *n_throw); // cout << Number of darts: *n_throw
MPI_Bcast(&n_throw, 1, MPI_LONG_LONG_INT, 0, MPI_COMM_WORLD); // Broadcast n_throw to all processes
start_time = MPI_Wtime(); // START Time
}
gettimeofday(&stime, NULL); // Time of the day
srand(stime.tv_usec * stime.tv_usec * stime.tv_usec * stime.tv_usec);
for (i=1; i<= *n_throw; i++){
x = RandomN(llimit, ulimit); // Random double between -1 & +1
y = RandomN(llimit, ulimit); // Random double between -1 & +1
z = pow(x,2) + pow(y,2); // Distance squared
if (z<=1.0){ // if Distance is squared <= 1.0
NC++; // number in circle ++
}
}
pi_estimate = 4.0 * (double)NC / (double) *n_throw; // PI estimate is (4 * number in circle) / number of tosses
MPI_Reduce (&pi_estimate, &pi_sum, 1, MPI_DOUBLE, MPI_SUM, M, MPI_COMM_WORLD); // Gather all the information to Master Processor.
if (p_rnk == M) {
pi_sum = pi_sum / p_sz; // SUM of PI value / Processor Size
end_time = MPI_Wtime(); // END Time
printf("The known value of PI : %11.10f \n", PI); // cout << Known value of PI : PI
printf("The estimated Value of PI : %11.10f\n", pi_sum); // cout << Estimated Value of PI : pi_sum
printf("Time : %10.8f\n\n", end_time - start_time); // cout << Time : total_time
}
MPI_Finalize(); // End MPI
return 0;
}
```