#include <cstdio>

#include <omp.h>

#include <random>

#include <faasm/input.h>

#include <faasm/shared_mem.h>

#define CHUNK_SIZE 100000

#define PI 3.14159

unsigned long genSeed()

{

int threadNum = omp_get_thread_num();

return threadNum * threadNum * 77 - 22 * threadNum + 1927;

}

int main(int argc, char** argv)

{

std::string inputData = faasm::getStringInput("4");

int nWorkers = std::stoi(inputData);

long result = 0;

int nTotal = nWorkers * CHUNK_SIZE;

FAASM_REDUCE(result, FAASM_TYPE_LONG, FAASM_OP_SUM)

#pragma omp parallel num_threads(nWorkers) default(none) shared(nTotal) \

reduction(+ : result)

{

// Different seed per thread

std::uniform_real_distribution<double> unif(0, 1);

std::mt19937_64 generator(genSeed());

#pragma omp for

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

double x = unif(generator);

double y = unif(generator);

if (x * x + y * y <= 1.0) {

result++;

}

}

}

float pi = 4 * ((float)result / (nTotal));

float error = abs(PI - pi);

std::string output = "Pi estimate: " + std::to_string(pi) + " (error " +

std::to_string(error) + ")\n";

printf("%s", output.c_str());

faasm::setStringOutput(output.c_str());

return 0;

}