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std::lognor...distribution(3)  C++ Standard Libary std::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 random
     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
	a
	2 I

	expa
	a
	a-

	(ln x - m)2
	2s2

	a
	a
	a

	The  parameters  m and s are, respectively, the mean and standard devia-
     tion 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 un-
     defined if
		   this is not one of float, double, or long double.

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

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)
	(C++11)
	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 <cmath>
      #include <iomanip>
      #include <iostream>
      #include <map>
      #include <random>
      #include <string>

      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 < 1e4; ++n)
	      ++hist[std::round(d(gen))];

	  for  (std::cout  <<  std::fixed << std::setprecision(1); auto [x, y] :
     hist)
	      std::cout << std::hex << x << ' ' << std::string(y / 200, '*')  <<
     '\n';
      }

Possible output:
      2
      3 ***
      4 *************
      5 ***************
      6 *********
      7 ****
      8 *
      9
      a
      b
      c

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

http://cppreference.com 	   2024.06.10	   std::lognor...distribution(3)
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