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| Member functions | ||||
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(C++11)(C++11) |
Defined in header <random> | ||
template<class RealType=double> class normal_distribution; | (since C++11) | |
Generates random numbers according to theNormal (or Gaussian) random number distribution. It is defined as:
| 1 |
| σ√2π |
| -1 |
| 2 |
| x-μ |
| σ |
Here\(\small\mu\)μ is theMean and\(\small\sigma\)σ is theStandard deviation (stddev).
std::normal_distribution satisfies all requirements ofRandomNumberDistribution.
Contents |
| RealType | - | The result type generated by the generator. The effect is undefined if this is not one offloat,double, orlongdouble. |
| Member type | Definition |
result_type(C++11) | RealType |
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 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] |
(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] |
#include <cmath>#include <iomanip>#include <iostream>#include <map>#include <random>#include <string> int main(){std::random_device rd{};std::mt19937 gen{rd()}; // Values near the mean are the most likely. Standard deviation// affects the dispersion of generated values from the mean. std::normal_distribution d{5.0,2.0}; // Draw a sample from the normal distribution and round it to an integer.auto random_int=[&d,&gen]{returnstd::lround(d(gen));}; std::map<long,unsigned> histogram{};for(auto n{10000}; n;--n)++histogram[random_int()]; for(constauto[k, v]: histogram)std::cout<<std::setw(2)<< k<<' '<<std::string(v/200,'*')<<'\n';}
Possible output:
-1 0 1 * 2 *** 3 ***** 4 ******** 5 ********* 6 ********* 7 ****** 8 *** 9 *1011
| 1. | Weisstein, Eric W. "Normal Distribution." From MathWorld — A Wolfram Web Resource. |
| 2. | Normal distribution — From Wikipedia. |
