std::piecewise_linear_distribution

template <class RealType = double> class piecewise_linear_distribution;

Piecewise linear distribution

Random number distribution that produces floating-point values that are distributed over a sequence of contiguous subintervals, of which the probability density at its boundaries is specified, as if defined by the following probability density function:

A set of n non-negative individual weights (the w's) for each of the n subinterval bounds (b_i) are set on construction. The probability density on the bounds is proportional to those weights in such a way that the integral that covers all possible values is exactly 1.0.
The probability of producing a value within each subinterval is the linear value in between the probability density of its bounds.

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 piecewise_linear_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 piecewise linear 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:

intervals: Intervals (public member function)

densities: Densities (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

// piecewise_linear_distribution
#include <iostream>
#include <array>
#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::array<double,3> intervals {0.0, 4.5, 9.0};
  std::array<double,3> weights {10.0, 0.0, 10.0};
  std::piecewise_linear_distribution<double>
    distribution (intervals.begin(),intervals.end(),weights.begin());

  int p[10]={};

  for (int i=0; i<nrolls; ++i) {
    int number = distribution(generator);
    ++p[number];
  }

  std::cout << "a piecewise_linear_distribution:" << std::endl;
  for (int i=0; i<9; ++i) {
    std::cout << i << "-" << i+1 << ": ";
    std::cout << std::string(p[i]*nstars/nrolls,'*') << std::endl;
  }
  return 0;
}

Possible output:

a piecewise_linear_distribution:
0-1: *******************
1-2: **************
2-3: *********
3-4: *****
4-5: *
5-6: *****
6-7: *********
7-8: **************
8-9: *******************

distributions

generators

other

member functions

non-member functions