llvm/libcxx/test/std/numerics/rand/rand.util/rand.util.canonical/generate_canonical.pass.cpp

//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

// <random>

// template<class RealType, size_t bits, class URNG>
//     RealType generate_canonical(URNG& g);

#include <random>

#include <cassert>
#include <limits>

#include "test_macros.h"
#include "truncate_fp.h"

int main(int, char**)
{
    {
        typedef std::minstd_rand0 E;
        typedef float F;
        E r;
        F f = std::generate_canonical<F, 0>(r);
        assert(f == truncate_fp((16807 - E::min()) / (static_cast<F>(E::max() - E::min()) + F(1))));
    }
    {
        typedef std::minstd_rand0 E;
        typedef float F;
        E r;
        F f = std::generate_canonical<F, 1>(r);
        assert(f == truncate_fp((16807 - E::min()) / (static_cast<F>(E::max() - E::min()) + F(1))));
    }
    {
        typedef std::minstd_rand0 E;
        typedef float F;
        E r;
        F f = std::generate_canonical<F, std::numeric_limits<F>::digits - 1>(r);
        assert(f == truncate_fp((16807 - E::min()) / (static_cast<F>(E::max() - E::min()) + F(1))));
    }
    {
        typedef std::minstd_rand0 E;
        typedef float F;
        E r;
        F f = std::generate_canonical<F, std::numeric_limits<F>::digits>(r);
        assert(f == truncate_fp((16807 - E::min()) / (static_cast<F>(E::max() - E::min()) + F(1))));
    }
    {
        typedef std::minstd_rand0 E;
        typedef float F;
        E r;
        F f = std::generate_canonical<F, std::numeric_limits<F>::digits + 1>(r);
        assert(f == truncate_fp((16807 - E::min()) / (static_cast<F>(E::max() - E::min()) + F(1))));
    }

    {
        typedef std::minstd_rand0 E;
        typedef double F;
        E r;
        F f = std::generate_canonical<F, 0>(r);
        assert(f == truncate_fp((16807 - E::min()) / (static_cast<F>(E::max() - E::min()) + F(1))));
    }
    {
        typedef std::minstd_rand0 E;
        typedef double F;
        E r;
        F f = std::generate_canonical<F, 1>(r);
        assert(f == truncate_fp((16807 - E::min()) / (static_cast<F>(E::max() - E::min()) + F(1))));
    }
    {
        typedef std::minstd_rand0 E;
        typedef double F;
        E r;
        F f = std::generate_canonical<F, std::numeric_limits<F>::digits - 1>(r);
        assert(f == truncate_fp(
            (16807 - E::min() +
            (282475249 - E::min()) * (static_cast<F>(E::max() - E::min()) + F(1))) /
            ((static_cast<F>(E::max() - E::min()) + F(1)) * (static_cast<F>(E::max() - E::min()) + F(1)))));
    }
    {
        typedef std::minstd_rand0 E;
        typedef double F;
        E r;
        F f = std::generate_canonical<F, std::numeric_limits<F>::digits>(r);
        assert(f == truncate_fp(
            (16807 - E::min() +
            (282475249 - E::min()) * (static_cast<F>(E::max() - E::min()) + F(1))) /
            ((static_cast<F>(E::max() - E::min()) + F(1)) * (static_cast<F>(E::max() - E::min()) + F(1)))));
    }
    {
        typedef std::minstd_rand0 E;
        typedef double F;
        E r;
        F f = std::generate_canonical<F, std::numeric_limits<F>::digits + 1>(r);
        assert(f == truncate_fp(
            (16807 - E::min() +
            (282475249 - E::min()) * (static_cast<F>(E::max() - E::min()) + F(1))) /
            ((static_cast<F>(E::max() - E::min()) + F(1)) * (static_cast<F>(E::max() - E::min()) + F(1)))));
    }

  return 0;
}