Files
multiprecision/example/cpp_double_fp_gamma_bessel.cpp
2025-06-19 13:28:31 +02:00

106 lines
3.9 KiB
C++

///////////////////////////////////////////////////////////////
// Copyright Christopher Kormanyos 2021 - 2025.
// Distributed under the Boost
// Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt
//
#include <iomanip>
#include <iostream>
// cd /mnt/c/Users/User/Documents/Ks/PC_Software/Test
// g++ -O3 -Wall -march=native -std=gnu++14 -I/mnt/c/MyGitRepos/BoostGSoC21_multiprecision/include -I/mnt/c/boost/boost_1_81_0 test.cpp -lquadmath -o test.exe
#include <boost/math/constants/constants.hpp>
#include <boost/math/special_functions/bessel.hpp>
#include <boost/math/special_functions/gamma.hpp>
#include <boost/multiprecision/cpp_double_fp.hpp>
#include <boost/multiprecision/cpp_dec_float.hpp>
template<typename FloatType>
void represent_tgamma_half()
{
// N[Sqrt[Pi], 101]
// 1.7724538509055160272981674833411451827975494561223871282138077898529112845910321813749506567385446654
std::cout << std::endl << "represent_tgamma_half" << std::endl;
using float_type = FloatType;
const float_type g = boost::math::tgamma(float_type(0.5F));
const float_type ctrl = sqrt(boost::math::constants::pi<float_type>());
const float_type delta = fabs(1 - (g / ctrl));
const auto flg = std::cout.flags();
std::cout << std::setprecision(std::numeric_limits<float_type>::digits10) << g << std::endl;
std::cout << std::setprecision(std::numeric_limits<float_type>::digits10) << ctrl << std::endl;
std::cout << std::scientific << std::setprecision(4) << delta << std::endl;
std::cout.flags(flg);
}
template<typename FloatType>
void represent_cyl_bessel_j()
{
// N[BesselJ[2, 345/100], 101]
// 0.46452112540537213897844513503677773921598161558478057526782559731407738667745222063644605126028883049
std::cout << std::endl << "represent_cyl_bessel_j" << std::endl;
using float_type = FloatType;
const float_type b = boost::math::cyl_bessel_j(2, float_type(345) / 100);
const float_type ctrl("0.46452112540537213897844513503677773921598161558478057526782559731407738667745222063644605126028883049");
const float_type delta = fabs(1 - (b / ctrl));
const auto flg = std::cout.flags();
std::cout << std::setprecision(std::numeric_limits<float_type>::digits10) << b << std::endl;
std::cout << std::setprecision(std::numeric_limits<float_type>::digits10) << ctrl << std::endl;
std::cout << std::scientific << std::setprecision(4) << delta << std::endl;
std::cout.flags(flg);
}
int main()
{
{
using double_float_type = boost::multiprecision::cpp_double_double;
using dec_float_type = boost::multiprecision::number<boost::multiprecision::cpp_dec_float<std::numeric_limits<double_float_type>::digits10>, boost::multiprecision::et_off>;
represent_tgamma_half<double_float_type>();
represent_tgamma_half<dec_float_type>();
represent_cyl_bessel_j<double_float_type>();
represent_cyl_bessel_j<dec_float_type>();
}
{
using double_float_type = boost::multiprecision::cpp_double_long_double;
using dec_float_type = boost::multiprecision::number<boost::multiprecision::cpp_dec_float<std::numeric_limits<double_float_type>::digits10>, boost::multiprecision::et_off>;
represent_tgamma_half<double_float_type>();
represent_tgamma_half<dec_float_type>();
represent_cyl_bessel_j<double_float_type>();
represent_cyl_bessel_j<dec_float_type>();
}
#if defined(BOOST_HAS_FLOAT128)
{
using double_float_type = boost::multiprecision::cpp_double_float128;
using dec_float_type = boost::multiprecision::number<boost::multiprecision::cpp_dec_float<std::numeric_limits<double_float_type>::digits10>, boost::multiprecision::et_off>;
represent_tgamma_half<double_float_type>();
represent_tgamma_half<dec_float_type>();
represent_cyl_bessel_j<double_float_type>();
represent_cyl_bessel_j<dec_float_type>();
}
#endif
}