import java.util.Random;

import com.arrayfire.*;

import static com.arrayfire.ArrayFire.*;

public class MonteCarloPi {

public static double hostCalcPi(int size) {

Random rand = new Random();

int count = 0;

for (int i = 0; i < size; i++) {

float x = rand.nextFloat();

float y = rand.nextFloat();

boolean lt1 = (x * x + y * y) < 1;

if (lt1)

count++;

}

return 4.0 * ((double) (count)) / size;

}

public static double deviceCalcPi(int size) throws Exception {

Array x = new Array(), y = new Array(), res = new Array();

try {

int[] dims = new int[] { size, 1 };

randu(x, dims, Type.Float);

randu(y, dims, Type.Float);

mul(x, x, x);

mul(y, y, y);

add(res, x, y);

lt(res, res, 1);

double count = sumAll(res);

return 4.0 * ((double) (count)) / size;

} catch (Exception e) {

throw e;

} finally {

x.close();

y.close();

res.close();

}

}

public static void main(String[] args) {

try {

int size = 5000000;

int iter = 100;

double devicePi = deviceCalcPi(size);

System.out.println("Results from device: " + devicePi);

double hostPi = hostCalcPi(size);

System.out.println("Results from host: " + hostPi);

long deviceStart = System.currentTimeMillis();

for (int i = 0; i < iter; i++) {

devicePi = deviceCalcPi(size);

}

double deviceElapsed = (double) (System.currentTimeMillis() - deviceStart) / iter;

System.out.println("Time taken for device (ms): " + deviceElapsed);

long hostStart = System.currentTimeMillis();

for (int i = 0; i < iter; i++) {

hostPi = hostCalcPi(size);

}

double hostElapsed = (double) (System.currentTimeMillis() - hostStart) / iter;

System.out.println("Time taken for host (ms): " + hostElapsed);

System.out.println("Speedup: " + Math.round((hostElapsed) / (deviceElapsed)));

} catch (Exception e) {

e.printStackTrace();

}

}

}