Re: improve <boost/math/constants.hpp>

From: Gero Peterhoff (g.peterhoff_at_[hidden])
Date: 2023-03-16 22:29:12

I forgot my test case

int main()
{
        std::cout << std::setprecision(100);
        std::cout << "boost pi" << std::endl;

        {
                const auto pi = boost::math::constants::pi<std::float16_t>();
                std::cout << pi << std::endl;
        }
        {
                constexpr auto pi = boost::math::constants::pi<std::float128_t>();
                std::cout << pi << std::endl;
        }
        {
                constexpr auto pi = boost::math::constants::pi<boost::multiprecision::float128>();
                std::cout << pi << std::endl;
        }
        {
                const auto pi = boost::math::constants::pi<boost::multiprecision::cpp_bin_float_100>();
                std::cout << pi << std::endl;
        }

        std::cout << "my pi" << std::endl;

        {
                constexpr auto pi = boost::math::constants::my_pi<std::float16_t>();
                std::cout << pi << std::endl;
        }
        {
                constexpr auto pi = boost::math::constants::my_pi<std::float128_t>();
                std::cout << pi << std::endl;
        }
        {
                constexpr auto pi = boost::math::constants::my_pi<boost::multiprecision::float128>();
                std::cout << pi << std::endl;
        }
        {
                const auto pi = boost::math::constants::my_pi<boost::multiprecision::cpp_bin_float_100>();
                std::cout << pi << std::endl;
        }

        return EXIT_SUCCESS;
}

boost pi
3.140625000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
3.141592653589793238462643383279502797479068098137295573004504331874296718662975536062731407582759857
3.141592653589793238462643383279502797479068098137295573004504331874296718662975536062731407582759857
3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342117068
my pi
3.140625000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
3.141592653589793238462643383279502797479068098137295573004504331874296718662975536062731407582759857
3.141592653589793238462643383279502797479068098137295573004504331874296718662975536062731407582759857
3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342117068