soft_double/examples/example012_exercise_constexpr.cpp at main · ckormanyos/soft_double · GitHub

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///////////////////////////////////////////////////////////////////

// Copyright Christopher Kormanyos 2023. //

// Distributed under the Boost Software License, //

// Version 1.0. (See accompanying file LICENSE_1_0.txt //

// or copy at http://www.boost.org/LICENSE_1_0.txt) //

///////////////////////////////////////////////////////////////////

#include <cmath>

#include <math/softfloat/soft_double.h>

#include <math/softfloat/soft_double_examples.h>

// Use a C++20 compiler for this example.

auto math::softfloat::example012_exercise_constexpr() -> bool

{

// Use a convenient alias for float64_t.

using ::math::softfloat::float64_t;

// Use a cached value for pi.

constexpr float64_t my_pi = float64_t::my_value_pi();

// Compute soft_double sqrt(pi).

#if (defined(_MSC_VER) && (_MSC_VER < 1920))

#pragma warning(push)

#pragma warning(disable : 4307)

#endif

constexpr float64_t s = sqrt(my_pi);

#if (defined(_MSC_VER) && (_MSC_VER < 1920))

#pragma warning(pop)

#endif

using std::sqrt;

// Compare with native double sqrt(pi).

// This is a non-constexpr, run-time comparison.

const auto result_root_non_constexpr_is_ok =

(s.crepresentation() == float64_t(sqrt(3.1415926535897932384626433832795028841972)).crepresentation());

constexpr auto result_root_as_constexpr_is_ok =

(s.crepresentation() == static_cast<typename float64_t::representation_type>(UINT64_C(0x3FFC5BF891B4EF6A)));

// constexpr verification.

// This is a compile-time comparison.

static_assert(result_root_as_constexpr_is_ok, "Error: example001_roots_sqrt not OK!");

const auto result_is_ok = (result_root_non_constexpr_is_ok && result_root_as_constexpr_is_ok);

return result_is_ok;

}

// Enable this if you would like to activate this main() as a standalone example.

#if 0 // NOLINT(readability-avoid-unconditional-preprocessor-if)

#include <iomanip>

#include <iostream>

auto main() -> int

{

const bool result_is_ok = math::softfloat::example012_exercise_constexpr();

std::cout << "result_is_ok: " << std::boolalpha << result_is_ok << std::endl;

}

#endif

soft_double/examples/example012_exercise_constexpr.cpp at main · ckormanyos/soft_double · GitHub

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