Value of Pi computed using Monte Carlo

montecarlo_pi.cpp

#include <iostream>
#include <vector>
#include <random>
#include <string>
#include <cmath>
#include <chrono>

using namespace std;
using namespace std::chrono;

struct Point2
{
	float x, y;
};

float distance(Point2 center, Point2 point)
{
	float cpx = (center.x - point.x);
	float cpy = (center.y - point.y);
	return sqrt(cpx*cpx + cpy*cpy);
}

bool isInCircle(Point2 center, float radius, Point2 point)
{
	return distance(center, point) <= radius;
}

int main()
{
	const unsigned int NB_SAMPLES = 10'000'000;

	const float sizeSquare = 2.;
	const float areaSquare = sizeSquare * sizeSquare;
	const float radius = 0.5*sizeSquare;
	const Point2 center = { radius,radius };

	random_device r;
	default_random_engine e1(r());
	uniform_real_distribution<float> uniform_dist(0.f, sizeSquare);

	unsigned int count = 0;
	float estimatedPi;

	auto before = system_clock::now();

	for (unsigned int i = 0; i < NB_SAMPLES; ++i)
	{
		// Generate a 2d point sample in [0,sizeSquare]x[0,sizeSquare]
		// Add to counter if the sample is in circle
		if (isInCircle(center, radius, { uniform_dist(e1) , uniform_dist(e1) }))
			count++;

		// Current Pi estimation
		estimatedPi = areaSquare * static_cast<float>(count) / static_cast<float>(i);
		// cout << "Estimated Pi : " << estimatedPi << "\n";
	}

	auto after = system_clock::now();
	auto deltaTime = duration_cast<seconds>(after - before).count();
	cout << "Estimated Pi : " << estimatedPi << " computed in " << deltaTime << " seconds" << "\n";
	cin >> estimatedPi;
}