public member function
<random>
| (1) | explicit normal_distribution ( result_type mean = 0.0, result_type stddev = 1.0 ); |
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| (2) | explicit normal_distribution ( const param_type& parm ); |
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Construct normal distribution
Constructs a normal_distribution object, adopting the distribution parameters specified either by mean and stddev or by object parm.
Parameters
- mean
- Mean of the distribution (its expected value, μ). Which coincides with the location of its peak.
result_type is a member type that represents the type of the random numbers generated on each call to operator(). It is defined as an alias of the first class template parameter (RealType).
- stddev
- Standard deviation (σ): The square root of variance, representing the dispersion of values from the distribution mean.
This shall be a positive value (σ>0).
result_type is a member type that represents the type of the random numbers generated on each call to operator(). It is defined as an alias of the first class template parameter (RealType).
- parm
- An object representing the distribution's parameters, obtained by a call to member function param.
param_type is a member type.
Example
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// normal_distribution example
#include <iostream>
#include <chrono>
#include <random>
int main()
{
// construct a trivial random generator engine from a time-based seed:
unsigned seed = std::chrono::system_clock::now().time_since_epoch().count();
std::default_random_engine generator (seed);
std::normal_distribution<double> distribution (0.0,1.0);
std::cout << "some Normal-distributed(0.0,1.0) results:" << std::endl;
for (int i=0; i<10; ++i)
std::cout << distribution(generator) << std::endl;
return 0;
}
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Possible output:
some Normal-distributed(0.0,1.0) results:
-0.246719
0.189872
-1.53603
-1.58534
0.0569692
2.22
1.34839
-0.512007
0.450768
-0.0999992
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