std::extreme_value_distribution - cppreference.com (original) (raw)

std::extreme_value_distribution

| | | | | ------------------------------------------------------------------------- | | ------------- | | template< class RealType = double > class extreme_value_distribution; | | (since C++11) |

Produces random numbers according to the Generalized extreme value distribution (it is also known as Gumbel Type I, log-Weibull, Fisher-Tippett Type I):

\({\small p(x;a,b) = \frac{1}{b} \exp{(\frac{a-x}{b}-\exp{(\frac{a-x}{b})})} }\)p(x;a,b) = exp⎛
⎜
⎝ - exp⎛
⎜
⎝⎞
⎟
⎠⎞
⎟
⎠

std::extreme_value_distribution satisfies all requirements of RandomNumberDistribution.

Contents

• 1 Template parameters
• 2 Member types
• 3 Member functions
  • 3.1 Generation
  • 3.2 Characteristics
• 4 Non-member functions
• 5 Example
• 6 External links

[edit] Template parameters

[edit] Member types

[edit] Member functions

[edit] Non-member functions

[edit] Example

#include #include #include #include #include #include #include   template void draw_vbars(Seq&& s, const bool DrawMinMax = true) { static_assert(0 < Height and 0 < BarWidth and 0 <= Padding and 0 <= Offset);   auto cout_n = [](auto&& v, int n = 1) { while (n-- > 0) std::cout << v; };   const auto [min, max] = std::minmax_element(std::cbegin(s), std::cend(s));   std::vector<std::div_t> qr; for (typedef decltype(*std::cbegin(s)) V; V e : s) qr.push_back(std::div(std::lerp(V(0), 8 * Height, (e - *min) / (*max - *min)), 8));   for (auto h{Height}; h-- > 0; cout_n('\n')) { cout_n(' ', Offset);   for (auto dv : qr) { const auto q{dv.quot}, r{dv.rem}; unsigned char d[]{0xe2, 0x96, 0x88, 0}; // Full Block: '█' q < h ? d[0] = ' ', d[1] = 0 : q == h ? d[2] -= (7 - r) : 0; cout_n(d, BarWidth), cout_n(' ', Padding); }   if (DrawMinMax && Height > 1) Height - 1 == h ? std::cout << "┬ " << *max: h ? std::cout << "│ " : std::cout << "┴ " << *min; } }   int main() { std::random_device rd{}; std::mt19937 gen{rd()};   std::extreme_value_distribution<> d{-1.618f, 1.618f};   const int norm = 10'000; const float cutoff = 0.000'3f;   std::map<int, int> hist{}; for (int n = 0; n != norm; ++n) ++hist[std::round(d(gen))];   std::vector bars; std::vector indices; for (const auto& [n, p] : hist) if (const float x = p * (1.0f / norm); x > cutoff) { bars.push_back(x); indices.push_back(n); }   draw_vbars<8,4>(bars);   for (int n : indices) std::cout << ' ' << std::setw(2) << n << " "; std::cout << '\n'; }

Possible output:

           ████ ▅▅▅▅                                                        ┬ 0.2186
           ████ ████                                                        │
      ▁▁▁▁ ████ ████ ▇▇▇▇                                                   │
      ████ ████ ████ ████                                                   │
      ████ ████ ████ ████ ▆▆▆▆                                              │
      ████ ████ ████ ████ ████ ▁▁▁▁                                         │
 ▄▄▄▄ ████ ████ ████ ████ ████ ████ ▃▃▃▃                                    │

▁▁▁▁ ████ ████ ████ ████ ████ ████ ████ ████ ▆▆▆▆ ▃▃▃▃ ▂▂▂▂ ▁▁▁▁ ▁▁▁▁ ▁▁▁▁ ▁▁▁▁ ┴ 0.0005 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10

[edit] External links