std::piecewise_linear_distribution

template< class RealType = double >
class piecewise_linear_distribution;

std::piecewise_linear_distribution produces random floating-point numbers, which are distributed according to a linear probability density function within each of the several subintervals [b
i, b
i+1). The distribution is such that the probability density at each interval boundary is exactly the predefined value p
i. The probability density for any b.

i≤x<b
i+1 is p
i

+ p
i+1

, where probability densities at interval boundaries p
k are calculated as w
k/S where S is the sum of all

(w
k+w
k+1)(b
k+1−b
k).

The set of interval boundaries b
i and the set of weights at boundaries w
i are the parameters of this distribution.

std::piecewise_linear_distribution satisfies all requirements of RandomNumberDistribution.

Template parameters

Member types

Member functions

Non-member functions

Example

#include <iostream>
#include <iomanip>
#include <string>
#include <map>
#include <random>
 
int main()
{
    std::random_device rd;
    std::mt19937 gen(rd());
    // increase the probability from 0 to 5
    // remain flat from 5 to 10
    // decrease from 10 to 15 at the same rate
    std::vector<double> i{0, 5, 10, 15};
    std::vector<double> w{0, 1,   1, 0};
    std::piecewise_linear_distribution<> d(i.begin(), i.end(), w.begin());
 
    std::map<int, int> hist;
    for(int n=0; n<10000; ++n) {
        ++hist[d(gen)];
    }
    for(auto p : hist) {
        std::cout << std::setw(2) << std::setfill('0') << p.first << ' '
            << std::string(p.second/100,'*') << '\n';
    }
}

00 *
01 ***
02 ****
03 ******
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11 *******
12 ****
13 ***
14 *