std::normal_distribution

template <class RealType = double> class normal_distribution;

Normal distribution
Random number distribution that produces floating-point values according to a normal distribution, which is described by the following probability density function: This distribution produces random numbers around the distribution mean (μ) with a specific standard deviation (σ).The normal distribution is a common distribution used for many kind of processes, since it is the distribution that the aggregation of a large number of independent random variables approximates to, when all follow the same distribution (no matter which distribution).The distribution parameters,  mean  (μ) and  stddev  (σ), are set on  construction .To produce a random value following this distribution, call its member function  operator() .

Template parameters

RealType
A floating-point type. Aliased as member type 
result_type.
By default, this is 
double.
 

Member types

The following aliases are member types of normal_distribution:
member type
definition
notes
result_type
The first template parameter (RealType)
The type of the numbers generated (defaults to double)
param_type
not specified
The type returned by member  param .
 

Member functions

(constructor)
Construct normal distribution 
(public member function)
operator()
Generate random number 
(public member function)
reset
Reset distribution 
(public member function)
param
Distribution parameters 
(public member function)
min
Minimum value 
(public member function )
max
Maximum value 
(public member function )
 

Distribution parameters:

normal_distribution::mean
Distribution mean 
(public member function)
normal_distribution::stddev
Standard deviation 
(public member function)
 

Non-member functions

operator<<
Insert into output stream 
(function template )
operator>>
Extract from input stream 
(function template )
relational operators
Relational operators 
(function template )
 

Example

   

 1 // normal_distribution

 2 #include <iostream>

 3 #include <random>

 4 

 5 int main()

 6 {

 7   const int nrolls=10000;  // number of experiments

 8   const int nstars=100;    // maximum number of stars to distribute

 9 

10   std::default_random_engine generator;

11   std::normal_distribution<double> distribution(5.0,2.0);

12 

13   int p[10]={};

14 

15   for (int i=0; i<nrolls; ++i) {

16     double number = distribution(generator);

17     if ((number>=0.0)&&(number<10.0)) ++p[int(number)];

18   }

19 

20   std::cout << "normal_distribution (5.0,2.0):" << std::endl;

21 

22   for (int i=0; i<10; ++i) {

23     std::cout << i << "-" << (i+1) << ": ";

24     std::cout << std::string(p[i]*nstars/nrolls,'*') << std::endl;

25   }

26 

27   return 0;

28 }

Possible output:

normal_distribution (5.0,2.0):

0-1: *

1-2: ****

2-3: *********

3-4: ***************

4-5: ******************

5-6: *******************

6-7: ***************

7-8: ********

8-9: ****

9-10: *