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      std::negative_binomial_distribution

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

      Produces random non-negative integer valuesi, distributed according to discrete probability function:

      \(P(i|k, p) = \binom{k + i - 1}{i} \cdot p^k \cdot (1 - p)^i\)P(i|k,p) =

      k + i − 1
      i


      · pk
      · (1 − p)i

      The value represents the number of failures in a series of independent yes/no trials (each succeeds with probabilityp), before exactlyk successes occur.

      std::negative_binomial_distribution satisfiesRandomNumberDistribution.

      Contents

      [edit]Template parameters

      IntType - The result type generated by the generator. The effect is undefined if this is not one ofshort,int,long,longlong,unsignedshort,unsignedint,unsignedlong, orunsignedlonglong.

      [edit]Member types

      Member type Definition
      result_type(C++11)IntType
      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 <iomanip>#include <iostream>#include <map>#include <random>#include <string> int main(){std::random_device rd;std::mt19937 gen(rd());// Pat goes door-to-door selling cookies// At each house, there's a 75% chance that she sells one box// how many times will she be turned away before selling 5 boxes?    std::negative_binomial_distribution<> d(5,0.75); std::map<int,int> hist;for(int n=0; n!=10000;++n)++hist[d(gen)]; for(auto[x, y]: hist)std::cout<<std::hex<< x<<' '<<std::string(y/100,'*')<<'\n';}

      Possible output:

      0 ***********************1 *****************************2 **********************3 *************4 ******5 ***6 *789ab

      [edit]External links

      Weisstein, Eric W. "Negative Binomial Distribution." From MathWorld — A Wolfram Web Resource.
      Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/numeric/random/negative_binomial_distribution&oldid=160834"

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