std::generate_canonical

 

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template< class RealType, size_t bits, class Generator > RealType generate_canonical( Generator& g );		(since C++11)

Generates a random floating point number in range [0; 1).

g() is called as many times as needed to generate enough entropy, i.e. at least max(1, ⌈ min(b
1, b
2) / log
2 R ⌉) times, where

• b1 = std::numeric_limits<RealType>::digits
• b2 = std::numeric_limits<RealType>::bits
• R = g.max() - g.min() + 1.

Parameters

g

-

generator to use to acquire entropy

Return value

Floating point value in range [0; 1).

Exceptions

None except from those thrown by g

Example

produce random numbers with 10 bits of randomness: this may produce only 1024 distinct values

#include <random>
#include <iostream>
 
int main()
{
    std::random_device rd;
    std::mt19937 gen(rd());
    for(int n=0; n<10; ++n) {
        std::cout << std::generate_canonical<double, 10>(gen) << ' ';
    }
}

Output:

0.208143 0.824147 0.0278604 0.343183 0.0173263 0.864057 0.647037 0.539467 0.0583497 0.609219

See also

uniform_real_distribution (C++11)	produces real values evenly distributed across a range (class template)