Reference

<random>

class template
<random>

std::cauchy_distribution

template <class RealType = double> class cauchy_distribution;
Cauchy distribution
Random number distribution that produces floating-point values according to a Cauchy distribution, which is described by the following probability density function:



This distribution produces random numbers as the result of dividing two independent standard normal random variables (Normal with μ=0.0 and σ=1.0), like a Student-t distribution with one degree of freedom.

The distribution parameters, a and b, 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 cauchy_distribution:

member typedefinitionnotes
result_typeThe first template parameter (RealType)The type of the numbers generated (defaults to double)
param_typenot specifiedThe type returned by member param.

Member functions

(constructor)
Construct Cachy 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:

a
Parameter a (public member function)
b
Parameter b (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

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// cauchy_distribution
#include <iostream>
#include <random>
int main()
{
 const int nrolls=10000; // number of experiments
 const int nstars=100; // maximum number of stars to distribute
 std::default_random_engine generator;
 std::cauchy_distribution<double> distribution(5.0,1.0);
 int p[10]={};
 for (int i=0; i<nrolls; ++i) {
 double number = distribution(generator);
 if ((number>=0.0)&&(number<10.0)) ++p[int(number)];
 }
 std::cout << "cauchy_distribution (5.0,1.0):" << std::endl;
 for (int i=0; i<10; ++i) {
 std::cout << i << "-" << (i+1) << ": ";
 std::cout << std::string(p[i]*nstars/nrolls,'*') << std::endl;
 }
 return 0;
}

Possible output:

cauchy_distribution (5.0,1.0):
0-1: *
1-2: **
2-3: ****
3-4: **********
4-5: ************************
5-6: *************************
6-7: *********
7-8: ****
8-9: **
9-10: *


See also

normal_distribution
Normal distribution (class template)
lognormal_distribution
Lognormal distribution (class template)
chi_squared_distribution
Chi-squared distribution (class template)
fisher_f_distribution
Fisher F-distribution (class template)
student_t_distribution
Student T-Distribution (class template)

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