pi.cpp

#include "rtweekend.h"

#include <iostream>
#include <iomanip>
#include <math.h>
#include <stdlib.h>

void estimatePI() {
    int inside_circle = 0;
    int inside_circle_stratified = 0;
    int sqrt_N = 10000;
    std::cout << std::fixed << std::setprecision(12);

    for (int i = 0; i < sqrt_N; ++i) {
        for (int j = 0; j < sqrt_N; ++j) {
            auto x = random_double(-1, 1);
            auto y = random_double(-1, 1);

            if (x * x + y * y < 1)
                inside_circle++;

            x = 2 * ((i + random_double()) / sqrt_N) - 1;
            y = 2 * ((j + random_double()) / sqrt_N) - 1;

            if (x * x + y * y < 1)
                inside_circle_stratified++;
        }
    }

    auto N = static_cast<double>(sqrt_N) * sqrt_N;
    std::cout << std::fixed << std::setprecision(12);
    std::cout
            << "Regular    Estimate of Pi = "
            << 4*double(inside_circle) / (sqrt_N*sqrt_N) << '\n'
            << "Stratified Estimate of Pi = "
            << 4*double(inside_circle_stratified) / (sqrt_N*sqrt_N) << '\n';
}