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std::lognor...distribution(3) C++ Standard Libarystd::lognor...distribution(3)

NAME
       std::lognormal_distribution - std::lognormal_distribution

Synopsis
	  Defined in header <random>
	  template< class RealType = double >  (since C++11)
	  class	lognormal_distribution;

	  The  lognormal_distribution random number distribution produces ran-
       dom numbers x > 0
	  according to a log-normal distribution:

		  \({\small f(x;m,s) = \frac{1}{sx\sqrt{2\pi} }	 \exp{(-\frac{
       {(\ln{x}	-
		  m)}^{2} }{2{s}^{2} })} }\)f(x; m,s) =

		  1
		  sx

		  2

		  exp

		  -

		  (ln x	- m)2
		  2s2

	  The  parameters m and	s are, respectively, the mean and standard de-
       viation of the
	  natural logarithm of x.

	  std::lognormal_distribution satisfies	all requirements of RandomNum-
       berDistribution

Template parameters
	  RealType - The result	type generated by the generator. The effect is
       undefined if
		     this is not one of	float, double, or long double.

Member types
	  Member type	    Definition
	  result_type	    RealType
	  param_type(C++11) the	type of	 the  parameter	 set,  see  RandomNum-
       berDistribution.

Member functions
	  constructor	constructs new distribution
	  (C++11)	(public	member function)
	  reset		resets the internal state of the distribution
	  (C++11)	(public	member function)

Generation
	  operator()	generates the next random number in the	distribution
	  (C++11)	(public	member function)

Characteristics
	  m		returns	the distribution parameters
	  s		(public	member function)
	  param		gets or	sets the distribution parameter	object
	  (C++11)	(public	member function)
	  min		returns	the minimum potentially	generated value
	  (C++11)	(public	member function)
	  max		returns	the maximum potentially	generated value
	  (C++11)	(public	member function)

Non-member functions
	  operator==
	  operator!=		    compares two distribution objects
	  (C++11)		    (function)
	  (C++11)(removed in C++20)
	  operator<<		      performs	stream	input  and  output  on
       pseudo-random number
	  operator>>		    distribution
	  (C++11)		    (function template)

Example
       // Run this code

	#include <iostream>
	#include <iomanip>
	#include <string>
	#include <map>
	#include <random>
	#include <cmath>
	int main()
	{
	    std::random_device rd;
	    std::mt19937 gen(rd());

	    std::lognormal_distribution<> d(1.6, 0.25);

	    std::map<int, int> hist;
	    for(int n=0; n<10000; ++n) {
		++hist[std::round(d(gen))];
	    }
	    for(auto p : hist) {
		std::cout   <<	 std::fixed   <<    std::setprecision(1)    <<
       std::setw(2)
			  <<  p.first << ' ' <<	std::string(p.second/200, '*')
       << '\n';
	    }
	}

Possible output:
	 2
	 3 ***
	 4 *************
	 5 ***************
	 6 *********
	 7 ****
	 8 *
	 9
	10
	11
	12

External links
	    * Weisstein, Eric W. "Log Normal Distribution." From  MathWorld--A
       Wolfram Web
	      Resource.

http://cppreference.com		  2022.07.31	 std::lognor...distribution(3)

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