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73 lines
2.6 KiB
C++
73 lines
2.6 KiB
C++
/**
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* \file MPFRUniform.hpp
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* \brief Header for MPFRUniform
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*
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* Sampling exactly from a uniform distribution for MPFR.
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*
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* Copyright (c) Charles Karney (2012) <charles@karney.com> and licensed under
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* the MIT/X11 License. For more information, see
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* http://randomlib.sourceforge.net/
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**********************************************************************/
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#if !defined(RANDOMLIB_MPFRUNIFORM_HPP)
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#define RANDOMLIB_MPFRUNIFORM_HPP 1
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#include <RandomLib/MPFRRandom.hpp>
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#if HAVE_MPFR || defined(DOXYGEN)
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namespace RandomLib {
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/**
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* \brief The uniform distribution for MPFR.
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*
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* This is just a thin layer on top of MPFRRandom to provide random numbers
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* uniformly distributed in [0,1].
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*
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* This class uses a mutable private object. So a single MPFRUniform object
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* cannot safely be used by multiple threads. In a multi-processing
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* environment, each thread should use a thread-specific MPFRUniform object.
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*
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* @tparam bits the number of bits in each digit.
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**********************************************************************/
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template<int bits = 32> class MPFRUniform {
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public:
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/**
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* Initialize the MPFRUniform object.
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**********************************************************************/
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MPFRUniform() {};
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/**
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* Sample from the uniform distribution in [0,1] returning a MPFRRandom.
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* This function takes an unused GMP random generator as a parameter, in
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* order to parallel the usage of MPFRExponential and MPFRNormal.
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*
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* @param[out] t the MPFRRandom result.
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* @param[in,out] r a GMP random generator (unused).
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**********************************************************************/
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void operator()(MPFRRandom<bits>& t, gmp_randstate_t r) const
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{ Compute(r); _x.swap(t); }
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/**
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* Sample from the uniform distribution in [0,1].
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*
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* @param[out] val the sample from the uniform distribution
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* @param[in,out] r a GMP random generator.
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* @param[in] round the rounding direction.
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* @return the MPFR ternary result (± if val is larger/smaller than
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* the exact sample).
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**********************************************************************/
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int operator()(mpfr_t val, gmp_randstate_t r, mpfr_rnd_t round) const
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{ Compute(r); return _x(val, r, round); }
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private:
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// disable copy constructor and assignment operator
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MPFRUniform(const MPFRUniform&);
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MPFRUniform& operator=(const MPFRUniform&);
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void Compute(gmp_randstate_t /* r */) const { _x. Init(); }
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mutable MPFRRandom<bits> _x;
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};
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} // namespace RandomLib
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#endif // HAVE_MPFR
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#endif // RANDOMLIB_MPFRUNIFORM_HPP
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