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| Mathematical constants(C++20) | |||||||||||||||||||||||||||||||
| Basic linear algebra algorithms(C++26) | |||||||||||||||||||||||||||||||
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| Complex numbers | |||||||||||||||||||||||||||||||
Numeric array (valarray) | |||||||||||||||||||||||||||||||
| Pseudo-random number generation | |||||||||||||||||||||||||||||||
| Bit manipulation(C++20) | |||||||||||||||||||||||||||||||
| Saturation arithmetic(C++26) | |||||||||||||||||||||||||||||||
| Factor operations | |||||||||||||||||||||||||||||||
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| Interpolations | |||||||||||||||||||||||||||||||
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| Generic numeric operations | |||||||||||||||||||||||||||||||
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| C-style checked integer arithmetic | |||||||||||||||||||||||||||||||
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| Member functions | ||||
| Generation | ||||
| Characteristics | ||||
| Non-member functions | ||||
(C++11)(C++11)(until C++20) | ||||
(C++11)(C++11) |
Defined in header <random> | ||
template<class RealType=double> class piecewise_linear_distribution; | (since C++11) | |
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\(\small{[b_i, b_{i+1})}\)[bi, bi+1). The distribution is such that the probability density at each interval boundary is exactly the predefined value\(\small{p_i}\)pi.
| bi+1-x |
| bi+1-bi |
| x-bi |
| bi+1-bi |
| 1 |
| 2 |
The set of interval boundaries\(\small{b_i}\)bi and the set of weights at boundaries\(\small{w_i}\)wi are the parameters of this distribution.
std::piecewise_linear_distribution satisfies all requirements ofRandomNumberDistribution.
Contents |
| RealType | - | The result type generated by the generator. The effect is undefined if this is not one offloat,double, orlongdouble. |
| Member type | Definition |
result_type(C++11) | RealType |
param_type(C++11) | the type of the parameter set, seeRandomNumberDistribution. |
(C++11) | constructs new distribution (public member function)[edit] |
(C++11) | resets the internal state of the distribution (public member function)[edit] |
Generation | |
(C++11) | generates the next random number in the distribution (public member function)[edit] |
Characteristics | |
(C++11) | returns the distribution parameters (public member function)[edit] |
(C++11) | gets or sets the distribution parameter object (public member function)[edit] |
(C++11) | returns the minimum potentially generated value (public member function)[edit] |
(C++11) | returns the maximum potentially generated value (public member function)[edit] |
(C++11)(C++11)(removed in C++20) | compares two distribution objects (function)[edit] |
(C++11) | performs stream input and output on pseudo-random number distribution (function template)[edit] |
#include <iomanip>#include <iostream>#include <map>#include <random>#include <string> 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 ratestd::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{}; n<1e4;++n)++hist[d(gen)]; for(auto[x, y]: hist)std::cout<<std::setw(2)<<std::setfill('0')<< x<<' '<<std::string(y/100,'*')<<'\n';}
Possible output:
00 *01 ***02 ****03 ******04 *********05 *********06 *********07 **********08 *********09 **********10 *********11 *******12 ****13 ***14 *
