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Switch to a simpler & faster uniform real generation algorithm

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This commit is contained in:
Nikita Lisitsa 2025-09-07 14:01:18 +03:00
parent 754b279b1a
commit be372ee007
1 changed files with 3 additions and 16 deletions
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19
libs/random/include/psemek/random/uniform_real.hpp
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@ -52,25 +52,12 @@ namespace psemek::random
template <typename RNG> template <typename RNG>
T uniform_real_distribution<T>::generate(RNG & rng) T uniform_real_distribution<T>::generate(RNG & rng)
{ {
// see https://en.cppreference.com/w/cpp/numeric/random/generate_canonical // Previously used an algorithm like in https://en.cppreference.com/w/cpp/numeric/random/generate_canonical
// But the simple algorithm here is way faster, so...
static constexpr std::size_t digits = std::numeric_limits<T>::digits;
static T const limit = std::pow<T>(2, digits);
T const R = static_cast<T>(rng.max()) - static_cast<T>(rng.min()) + 1; T const R = static_cast<T>(rng.max()) - static_cast<T>(rng.min()) + 1;
T mult = T(1); return static_cast<T>(rng() - rng.min()) / R;
T sum = T(0);
while (mult < limit)
{
T inc = static_cast<T>(rng() - rng.min());
sum += inc * mult;
mult *= R;
}
return sum / mult;
} }
} }