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).
To generate enough entropy, generate_canonical()
will call g()
exactly k times, where k = max(1, ⌈ b / log
2 R ⌉) and.
-
b = std::min<std::size_t>(bits, std::numeric_limits<RealType>::digits)
-
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
.
Notes
Some existing implementations have a bug where they may occasionally return 1.0
if RealType
is float
GCC #63176 LLVM #18767. This is LWG issue 2524
Example
produce random numbers with 10 bits of randomness: this may produce only k*R 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
(C++11) | produces real values evenly distributed across a range (class template) |
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