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Class template additive_combine

boost::random::additive_combine

Synopsis

// In header: <boost/random/additive_combine.hpp>

template<typename MLCG1, typename MLCG2, typename MLCG1::result_type val> 
class additive_combine {
public:
  // types
  typedef MLCG1              first_base; 
  typedef MLCG2              second_base;
  typedef MLCG1::result_type result_type;

  // construct/copy/destruct
  additive_combine();
  additive_combine(result_type);
  additive_combine(typename MLCG1::result_type, typename MLCG2::result_type);
  template<typename It> additive_combine(It &, It);

  // public member functions
  result_type min() const;
  result_type max() const;
  void seed();
  void seed(result_type);
  void seed(typename MLCG1::result_type, typename MLCG2::result_type);
  template<typename It> void seed(It &, It);
  result_type operator()();

  // public static functions
  static bool validation(result_type);

  // friend functions
  template<typename CharT, typename Traits> 
    friend std::basic_ostream< CharT, Traits > & 
    operator<<(std::basic_ostream< CharT, Traits > &, 
               const additive_combine &);
  template<typename CharT, typename Traits> 
    friend std::basic_istream< CharT, Traits > & 
    operator>>(std::basic_istream< CharT, Traits > &, additive_combine &);
  friend bool operator==(const additive_combine &, const additive_combine &);
  friend bool operator!=(const additive_combine &, const additive_combine &);
  static const bool has_fixed_range;
  static const result_type min_value;
  static const result_type max_value;
};

Description

An instantiation of class template additive_combine model a pseudo-random number generator . It combines two multiplicative linear_congruential number generators, i.e. those with c = 0. It is described in

"Efficient and Portable Combined Random Number Generators", Pierre L'Ecuyer, Communications of the ACM, Vol. 31, No. 6, June 1988, pp. 742-749, 774

The template parameters MLCG1 and MLCG2 shall denote two different linear_congruential number generators, each with c = 0. Each invocation returns a random number X(n) := (MLCG1(n) - MLCG2(n)) mod (m1 - 1), where m1 denotes the modulus of MLCG1.

The template parameter val is the validation value checked by validation.

additive_combine public construct/copy/destruct

  1. additive_combine();

    Constructs an additive_combine generator using the default constructors of the two base generators.

  2. additive_combine(result_type aseed);

    Constructs an additive_combine generator, using aseed as the constructor argument for both base generators.

  3. additive_combine(typename MLCG1::result_type seed1, 
                     typename MLCG2::result_type seed2);

    Constructs an additive_combine generator, using seed1 and seed2 as the constructor argument to the first and second base generators, respectively.

  4. template<typename It> additive_combine(It & first, It last);

    Contructs an additive_combine generator with values from the range defined by the input iterators first and last. first will be modified to point to the element after the last one used.

    Throws: std::invalid_argument if the input range is too small.

    Exception Safety: Basic

additive_combine public member functions

  1. result_type min() const;

    Returns: The smallest value that the generator can produce

  2. result_type max() const;

    Returns: The largest value that the generator can produce

  3. void seed();

    Seeds an additive_combine generator using the default seeds of the two base generators.

  4. void seed(result_type aseed);

    Seeds an additive_combine generator, using aseed as the seed for both base generators.

  5. void seed(typename MLCG1::result_type seed1, 
              typename MLCG2::result_type seed2);

    Seeds an additive_combine generator, using seed1 and seed2 as the seeds to the first and second base generators, respectively.

  6. template<typename It> void seed(It & first, It last);

    Seeds an additive_combine generator with values from the range defined by the input iterators first and last. first will be modified to point to the element after the last one used.

    Throws: std::invalid_argument if the input range is too small.

    Exception Safety: Basic

  7. result_type operator()();

    Returns: the next value of the generator

additive_combine public static functions

  1. static bool validation(result_type x);

additive_combine friend functions

  1. template<typename CharT, typename Traits> 
      friend std::basic_ostream< CharT, Traits > & 
      operator<<(std::basic_ostream< CharT, Traits > & os, 
                 const additive_combine & r);

    Writes the state of an additive_combine generator to a std::ostream. The textual representation of an additive_combine generator is the textual representation of the first base generator followed by the textual representation of the second base generator.

  2. template<typename CharT, typename Traits> 
      friend std::basic_istream< CharT, Traits > & 
      operator>>(std::basic_istream< CharT, Traits > & is, additive_combine & r);

    Reads the state of an additive_combine generator from a std::istream.

  3. friend bool operator==(const additive_combine & x, const additive_combine & y);

    Returns: true iff the two additive_combine generators will produce the same sequence of values.

  4. friend bool operator!=(const additive_combine & x, const additive_combine & y);

    Returns: true iff the two additive_combine generators will produce different sequences of values.


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