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(C++11)(C++11)(until C++20) | ||||
(C++11)(C++11) |
Defined in header <random> | ||
template<class IntType=int> class geometric_distribution; | (since C++11) | |
Produces random non-negative integer valuesi, distributed according to discrete probability function:
The value represents the number of failures in a series of independent yes/no trials (each succeeds with probability p), before exactly 1 success occurs.
std::geometric_distribution<>(p) is exactly equivalent tostd::negative_binomial_distribution<>(1, p). It is also the discrete counterpart ofstd::exponential_distribution.
std::geometric_distribution satisfiesRandomNumberDistribution.
Contents |
| 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. |
| Member type | Definition |
result_type(C++11) | IntType |
param_type(C++11) | the type of the parameter set, seeRandomNumberDistribution. |
(C++11) | 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 thep distribution parameter (probability of a trial generatingtrue) (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] |
(C++11)(C++11)(removed in C++20) | compares two distribution objects (function)[edit] |
(C++11) | performs stream input and output on pseudo-random number distribution (function template)[edit] |
std::geometric_distribution<>(0.5) is the default and represents the number of coin tosses that are required to get heads.
#include <iomanip>#include <iostream>#include <map>#include <random>#include <string> int main(){std::random_device rd;std::mt19937 gen(rd()); std::geometric_distribution<> d;// same as// std::negative_binomial_distribution<> d(1, 0.5): std::map<int,int> hist;for(int n=0; n!=10000;++n)++hist[d(gen)]; for(auto[x, y]: hist){constchar c= x<10? x+'0': x-10+'a';std::cout<< c<<' '<<std::string(y/100,'*')<<'\n';}}
Possible output:
0 *************************************************1 *************************2 ************3 ******4 **5 *6789
| Weisstein, Eric W. "Geometric Distribution." From MathWorld — A Wolfram Web Resource. |
