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///
/// @file alpha_y.cpp
/// @brief Test the alpha_y tuning factor in Gourdon's algorithm.
/// y = alpha_y * x^(1/3)
/// By computing pi(x) using different alpha_y tuning
/// factors we can make sure that all array sizes
/// (and other bounds) are accurate.
///
/// Copyright (C) 2019 Kim Walisch, <kim.walisch@gmail.com>
///
/// This file is distributed under the BSD License. See the COPYING
/// file in the top level directory.
///
#include <gourdon.hpp>
#include <primecount.hpp>
#include <primecount-internal.hpp>
#include <imath.hpp>
#include <stdint.h>
#include <iostream>
#include <cstdlib>
#include <random>
using namespace primecount;
void check(bool OK)
{
std::cout << " " << (OK ? "OK" : "ERROR") << "\n";
if (!OK)
std::exit(1);
}
int main()
{
std::random_device rd;
std::mt19937 gen(rd());
int64_t min = (int64_t) 1e9;
int64_t max = min * 2;
std::uniform_int_distribution<int64_t> dist(min, max);
int threads = get_num_threads();
for (int i = 0; i < 20; i++)
{
int64_t x = dist(gen);
int64_t res1 = pi_meissel(x, threads);
for (double alpha_y = 1; alpha_y <= iroot<6>(x); alpha_y++)
{
set_alpha_y(alpha_y);
int64_t res2 = pi_gourdon(x, threads);
std::cout << "pi_gourdon(" << x << ") = " << res2;
check(res1 == res2);
}
}
std::cout << std::endl;
std::cout << "All tests passed successfully!" << std::endl;
return 0;
}
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