Line data    Source code

       1             : ///////////////////////////////////////////////////////////////////////////
       2             : // Spetabaru - Berenger Bramas MPCDF - 2017
       3             : // Under LGPL Licence, please you must read the LICENCE file.
       4             : ///////////////////////////////////////////////////////////////////////////
       5             : #ifndef SPMTGENERATOR_HPP
       6             : #define SPMTGENERATOR_HPP
       7             : 
       8             : #include <random>
       9             : 
      10             : /**
      11             :  * The is a random generator based on mt19937.
      12             :  * It supports skipping values, but it is simply an emulation,
      13             :  * because to skip N values, the generator calls N times rand.
      14             :  * Therefore, it is adequate for testing but should not be used
      15             :  * when performance is important.
      16             :  */
      17             : template <class RealType = double>
      18             : class SpMTGenerator {
      19             :     std::mt19937_64 mtEngine;
      20             :     std::uniform_real_distribution<RealType> dis01;
      21             :     std::size_t nbValuesGenerated;
      22             : 
      23             : public:
      24             :     explicit SpMTGenerator() : mtEngine(std::random_device()()), dis01(0,1), nbValuesGenerated(0){}
      25             : 
      26         584 :     explicit SpMTGenerator(const size_t inSeed) : mtEngine(inSeed), dis01(0,1), nbValuesGenerated(0){}
      27             : 
      28             :     SpMTGenerator(const SpMTGenerator&) = default;
      29             :     SpMTGenerator(SpMTGenerator&&) = default;
      30             :     SpMTGenerator& operator=(const SpMTGenerator&) = default;
      31             :     SpMTGenerator& operator=(SpMTGenerator&&) = default;
      32             : 
      33      207284 :     SpMTGenerator& skip(const size_t inNbToSeep){
      34             :         // To skip a value, we call rand() and do not use
      35             :         // the result of the call.
      36     3969996 :         for(size_t idx = 0 ; idx < inNbToSeep ; ++idx){
      37     3762712 :             getRand01();
      38             :         }
      39      207284 :         return *this;
      40             :     }
      41             : 
      42     4050536 :     RealType getRand01(){
      43     4050536 :         nbValuesGenerated += 1;
      44     4050536 :         return dis01(mtEngine);
      45             :     }
      46             : 
      47             :     size_t getNbValuesGenerated() const{
      48             :         return nbValuesGenerated;
      49             :     }
      50             : };
      51             : 
      52             : #endif