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///
/// @file alpha_lmo.cpp
/// @brief Test the alpha tuning factor with the LMO algorithm.
/// y = alpha * x^(1/3)
/// By computing pi(x) using different alpha tuning
/// factors we can make sure that all array sizes
/// (and other bounds) are accurate.
///
/// Copyright (C) 2023 Kim Walisch, <kim.walisch@gmail.com>
///
/// This file is distributed under the BSD License. See the COPYING
/// file in the top level directory.
///
#include <primecount.hpp>
#include <primecount-internal.hpp>
#include <imath.hpp>
#include <stdint.h>
#include <iostream>
#include <cstdlib>
#include <random>
#include <vector>
using namespace primecount;
void check(bool OK)
{
std::cout << " " << (OK ? "OK" : "ERROR") << "\n";
if (!OK)
std::exit(1);
}
int main()
{
int threads = get_num_threads();
// Test small x
{
std::random_device rd;
std::mt19937 gen(rd());
std::uniform_int_distribution<int64_t> dist(100, 1000);
for (int i = 0; i < 100; i++)
{
int64_t x = dist(gen);
int64_t res1 = pi_cache(x);
for (double alpha = 1; alpha <= iroot<6>(x); alpha++)
{
set_alpha(alpha);
int64_t res2 = pi_lmo_parallel(x, threads);
std::cout << "alpha = " << alpha << ", pi_lmo_parallel(" << x << ") = " << res2;
check(res2 == res1);
}
}
}
// Test medium x
{
int64_t min = (int64_t) 1e3;
int64_t max = (int64_t) 2e7;
std::random_device rd;
std::mt19937 gen(rd());
std::uniform_int_distribution<int64_t> dist(min, max);
for (int i = 0; i < 50; i++)
{
int64_t x = dist(gen);
int64_t res1 = pi_meissel(x, threads);
for (double alpha = 1; alpha <= iroot<6>(x); alpha++)
{
set_alpha(alpha);
int64_t res2 = pi_lmo_parallel(x, threads);
std::cout << "alpha = " << alpha << ", pi_lmo_parallel(" << x << ") = " << res2;
check(res2 == res1);
}
}
}
// Test large x
{
int64_t x = 9999999929ll;
int64_t res1 = 455052509ll;
std::vector<double> alphas = { 1, 1+1/3.0, 2, 10, (double) iroot<6>(x) };
for (double alpha : alphas)
{
set_alpha(alpha);
int64_t res2 = pi_lmo_parallel(x, threads);
std::cout << "alpha = " << alpha << ", pi_lmo_parallel(" << x << ") = " << res2;
check(res2 == res1);
}
}
std::cout << std::endl;
std::cout << "All tests passed successfully!" << std::endl;
return 0;
}
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