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      std::weibull_distribution

      From cppreference.com
      <cpp‎ |numeric‎ |random
       
       
       
      Pseudo-random number generation
       
       
      Defined in header<random>
      template<class RealType=double>
      class weibull_distribution;
      (since C++11)

      Theweibull_distribution meets the requirements of aRandomNumberDistribution and produces random numbers according to theWeibull distribution:

      \(\small{f(x;a,b)=\frac{a}{b}{(\frac{x}{b})}^{a-1}\exp{(-{(\frac{x}{b})}^{a})} }\)f(x;a,b) =
      a
      b


      x
      b


      a-1
      exp

      -

      x
      b


      a


      a is theshape parameter andb thescale parameter.

      std::weibull_distribution satisfiesRandomNumberDistribution.

      Contents

      [edit]Template parameters

      RealType - The result type generated by the generator. The effect is undefined if this is not one offloat,double, orlongdouble.

      [edit]Member types

      Member type Definition
      result_type(C++11)RealType
      param_type(C++11) the type of the parameter set, seeRandomNumberDistribution.

      [edit]Member functions

      constructs new distribution
      (public member function)[edit]
      (C++11)
      resets the internal state of the distribution
      (public member function)[edit]
      Generation
      (C++11)
      generates the next random number in the distribution
      (public member function)[edit]
      Characteristics
      (C++11)
      returns the distribution parameters
      (public member function)[edit]
      (C++11)
      gets or sets the distribution parameter object
      (public member function)[edit]
      (C++11)
      returns the minimum potentially generated value
      (public member function)[edit]
      (C++11)
      returns the maximum potentially generated value
      (public member function)[edit]

      [edit]Non-member functions

      (C++11)(C++11)(removed in C++20)
      compares two distribution objects
      (function)[edit]
      performs stream input and output on pseudo-random number distribution
      (function template)[edit]

      [edit]Example

      Run this code
      #include <cmath>#include <iomanip>#include <iostream>#include <map>#include <random>#include <string> int main(){std::random_device rd;std::mt19937 gen(rd());     std::weibull_distribution<> d; std::map<int,int> hist;for(int n=0; n!=10000;++n)++hist[std::round(d(gen))]; std::cout<<std::fixed<<std::setprecision(1)<<std::hex;for(auto[x, y]: hist)std::cout<< x<<' '<<std::string(y/200,'*')<<'\n';}

      Possible output:

      0 *******************1 *******************2 ******3 **45678

      [edit]External links

      1. Weisstein, Eric W. "Weibull Distribution." From MathWorld — A Wolfram Web Resource.
      2. Weibull distribution — From Wikipedia.
      Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/numeric/random/weibull_distribution&oldid=178565"

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