Gabriele Cosmo
107 lines
3.1 KiB
C++
107 lines
3.1 KiB
C++
//
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// -*- C++ -*-
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//
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// -----------------------------------------------------------------------
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// HEP Random
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// --- RanluxppEngine ---
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// class header file
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// -----------------------------------------------------------------------
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// Implementation of the RANLUX++ generator
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//
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// RANLUX++ is an LCG equivalent of RANLUX using 576 bit numbers.
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//
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// References:
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// A. Sibidanov
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// A revision of the subtract-with-borrow random numbergenerators
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// Computer Physics Communications, 221(2017), 299-303
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//
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// J. Hahnfeld, L. Moneta
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// A Portable Implementation of RANLUX++
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// vCHEP2021
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#ifndef RanluxppEngine_h
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#define RanluxppEngine_h
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#include "CLHEP/Random/RandomEngine.h"
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#include <cstdint>
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namespace CLHEP {
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/**
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* @author Jonas Hahnfeld
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* @ingroup random
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*/
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class RanluxppEngine final : public HepRandomEngine {
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public:
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RanluxppEngine();
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RanluxppEngine(long seed);
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RanluxppEngine(std::istream &is);
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virtual ~RanluxppEngine();
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// Constructors and destructor
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double flat() override;
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// It returns a pseudo random number between 0 and 1,
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// excluding the end points.
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void flatArray(const int size, double *vect) override;
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// Fills the array "vect" of specified size with flat random values.
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void setSeed(long seed, int dummy = 0) override;
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// Sets the state of the algorithm according to seed.
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void setSeeds(const long *seeds, int dummy = 0) override;
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// Sets the state of the algorithm according to the zero terminated
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// array of seeds. Only the first seed is used.
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void skip(uint64_t n);
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// Skip `n` random numbers without generating them.
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void saveStatus(const char filename[] = "Ranluxpp.conf") const override;
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// Saves in named file the current engine status.
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void restoreStatus(const char filename[] = "Ranluxpp.conf") override;
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// Reads from named file the last saved engine status and restores it.
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void showStatus() const override;
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// Dumps the engine status on the screen.
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std::string name() const override;
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// Optional methods to serialize the engine's state into vectors and streams.
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static std::string engineName();
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static std::string beginTag();
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std::ostream &put(std::ostream &os) const override;
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std::istream &get(std::istream &is) override;
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std::istream &getState(std::istream &is) override;
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std::vector<unsigned long> put() const override;
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bool get(const std::vector<unsigned long> &v) override;
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bool getState(const std::vector<unsigned long> &v) override;
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// Save and restore to/from streams
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operator double() override { return flat(); }
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operator float() override { return float(flat()); }
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operator unsigned int() override { return (unsigned int)nextRandomBits(); }
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// 1 value for the engine ID, 2 * 9 values for the state, and 2 more values
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// for the carry bit and the position.
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static const unsigned int VECTOR_STATE_SIZE = 21;
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private:
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void advance();
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uint64_t nextRandomBits();
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uint64_t fState[9]; ///< RANLUX state of the generator
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unsigned fCarry; ///< Carry bit of the RANLUX state
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int fPosition = 0; ///< Current position in bits
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}; // RanluxppEngine
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} // namespace CLHEP
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#endif
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