# std::piecewise_constant_distribution

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

`std::piecewise_constant_distribution` produces random floating-point numbers, which are uniformly distributed within each of the several subintervals [b
i
, b
i+1
)
, each with its own weight w
i
. The set of interval boundaries and the set of weights are the parameters of this distribution.

The probability density for any b
i
≤x<b
i+1
is
 wk S (bi+1 - bi)
. where S is the sum of all weights.

## Contents

### Member functions

constructs new distribution
(public member function) 
resets the internal state of the distribution
(public member function) 
##### Generation
generates the next random number in the distribution
(public member function) 
##### Characteristics
obtains the list of interval boundaries
(public member function) 
obtains the list of probability densities
(public member function) 
gets or sets the distribution parameter object
(public member function) 
returns the minimum potentially generated value
(public member function) 
returns the maximum potentially generated value
(public member function) 

### Non-member functions

 operator==operator!= compares two distribution objects (function)  operator<> performs stream input and output on pseudo-random number distribution (function) 

### Example

```#include <iostream>
#include <string>
#include <map>
#include <random>

int main()
{
std::random_device rd;
std::mt19937 gen(rd());
// 50% of the time, generate a random number between 0 and 1
// 50% of the time, generate a random number between 10 and 15
std::vector<double> i{0,  1, 10, 15};
std::vector<double> w{  1,  0,  1};
std::piecewise_constant_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 << p.first << ' ' << std::string(p.second/100, '*') << '\n';
}
}```

Output:

```0 **************************************************
10 **********
11 *********
12 *********
13 **********
14 *********```