29 Numerics library [numerics]

29.6 Random number generation [rand]

29.6.8 Random number distribution class templates [rand.dist]

29.6.8.5 Normal distributions [rand.dist.norm]

29.6.8.5.1 Class template normal_­distribution [rand.dist.norm.normal]

A normal_­distribution random number distribution produces random numbers x distributed according to the probability density function

The distribution parameters μ and σ are also known as this distribution's mean and standard deviation.

template<class RealType = double>
  class normal_distribution {
  public:
    // types
    using result_type = RealType;
    using param_type  = unspecified;

    // constructors and reset functions
    explicit normal_distribution(RealType mean = 0.0, RealType stddev = 1.0);
    explicit normal_distribution(const param_type& parm);
    void reset();

    // generating functions
    template<class URBG>
      result_type operator()(URBG& g);
    template<class URBG>
      result_type operator()(URBG& g, const param_type& parm);

    // property functions
    RealType mean() const;
    RealType stddev() const;
    param_type param() const;
    void param(const param_type& parm);
    result_type min() const;
    result_type max() const;
  };

explicit normal_distribution(RealType mean = 0.0, RealType stddev = 1.0);

Requires: .

Effects: Constructs a normal_­distribution object; mean and stddev correspond to the respective parameters of the distribution.

RealType mean() const;

Returns: The value of the mean parameter with which the object was constructed.

RealType stddev() const;

Returns: The value of the stddev parameter with which the object was constructed.

29.6.8.5.2 Class template lognormal_­distribution [rand.dist.norm.lognormal]

A lognormal_­distribution random number distribution produces random numbers distributed according to the probability density function

template<class RealType = double>
  class lognormal_distribution {
  public:
    // types
    using result_type = RealType;
    using param_type  = unspecified;

    // constructor and reset functions
    explicit lognormal_distribution(RealType m = 0.0, RealType s = 1.0);
    explicit lognormal_distribution(const param_type& parm);
    void reset();

    // generating functions
    template<class URBG>
      result_type operator()(URBG& g);
    template<class URBG>
      result_type operator()(URBG& g, const param_type& parm);

    // property functions
    RealType m() const;
    RealType s() const;
    param_type param() const;
    void param(const param_type& parm);
    result_type min() const;
    result_type max() const;
  };

explicit lognormal_distribution(RealType m = 0.0, RealType s = 1.0);

Requires: .

Effects: Constructs a lognormal_­distribution object; m and s correspond to the respective parameters of the distribution.

RealType m() const;

Returns: The value of the m parameter with which the object was constructed.

RealType s() const;

Returns: The value of the s parameter with which the object was constructed.

29.6.8.5.3 Class template chi_­squared_­distribution [rand.dist.norm.chisq]

A chi_­squared_­distribution random number distribution produces random numbers x>0 distributed according to the probability density function

template<class RealType = double>
  class chi_squared_distribution {
  public:
    // types
    using result_type = RealType;
    using param_type  = unspecified;

    // constructor and reset functions
    explicit chi_squared_distribution(RealType n = 1);
    explicit chi_squared_distribution(const param_type& parm);
    void reset();

    // generating functions
    template<class URBG>
      result_type operator()(URBG& g);
    template<class URBG>
      result_type operator()(URBG& g, const param_type& parm);

    // property functions
    RealType n() const;
    param_type param() const;
    void param(const param_type& parm);
    result_type min() const;
    result_type max() const;
  };

explicit chi_squared_distribution(RealType n = 1);

Requires: .

Effects: Constructs a chi_­squared_­distribution object; n corresponds to the parameter of the distribution.

RealType n() const;

Returns: The value of the n parameter with which the object was constructed.

29.6.8.5.4 Class template cauchy_­distribution [rand.dist.norm.cauchy]

A cauchy_­distribution random number distribution produces random numbers x distributed according to the probability density function

template<class RealType = double>
  class cauchy_distribution {
  public:
    // types
    using result_type = RealType;
    using param_type  = unspecified;

    // constructor and reset functions
    explicit cauchy_distribution(RealType a = 0.0, RealType b = 1.0);
    explicit cauchy_distribution(const param_type& parm);
    void reset();

    // generating functions
    template<class URBG>
      result_type operator()(URBG& g);
    template<class URBG>
      result_type operator()(URBG& g, const param_type& parm);

    // property functions
    RealType a() const;
    RealType b() const;
    param_type param() const;
    void param(const param_type& parm);
    result_type min() const;
    result_type max() const;
  };

explicit cauchy_distribution(RealType a = 0.0, RealType b = 1.0);

Requires: .

Effects: Constructs a cauchy_­distribution object; a and b correspond to the respective parameters of the distribution.

RealType a() const;

Returns: The value of the a parameter with which the object was constructed.

RealType b() const;

Returns: The value of the b parameter with which the object was constructed.

29.6.8.5.5 Class template fisher_­f_­distribution [rand.dist.norm.f]

A fisher_­f_­distribution random number distribution produces random numbers x≥0 distributed according to the probability density function

template<class RealType = double>
  class fisher_f_distribution {
  public:
    // types
    using result_type = RealType;
    using param_type  = unspecified;

    // constructor and reset functions
    explicit fisher_f_distribution(RealType m = 1, RealType n = 1);
    explicit fisher_f_distribution(const param_type& parm);
    void reset();

    // generating functions
    template<class URBG>
      result_type operator()(URBG& g);
    template<class URBG>
      result_type operator()(URBG& g, const param_type& parm);

    // property functions
    RealType m() const;
    RealType n() const;
    param_type param() const;
    void param(const param_type& parm);
    result_type min() const;
    result_type max() const;
  };

explicit fisher_f_distribution(RealType m = 1, RealType n = 1);

Requires: and .

Effects: Constructs a fisher_­f_­distribution object; m and n correspond to the respective parameters of the distribution.

RealType m() const;

Returns: The value of the m parameter with which the object was constructed.

RealType n() const;

Returns: The value of the n parameter with which the object was constructed.

29.6.8.5.6 Class template student_­t_­distribution [rand.dist.norm.t]

A student_­t_­distribution random number distribution produces random numbers x distributed according to the probability density function

template<class RealType = double>
  class student_t_distribution {
  public:
    // types
    using result_type = RealType;
    using param_type  = unspecified;

    // constructor and reset functions
    explicit student_t_distribution(RealType n = 1);
    explicit student_t_distribution(const param_type& parm);
    void reset();

    // generating functions
    template<class URBG>
      result_type operator()(URBG& g);
    template<class URBG>
      result_type operator()(URBG& g, const param_type& parm);

    // property functions
    RealType n() const;
    param_type param() const;
    void param(const param_type& parm);
    result_type min() const;
    result_type max() const;
  };

explicit student_t_distribution(RealType n = 1);

Requires: .

Effects: Constructs a student_­t_­distribution object; n corresponds to the parameter of the distribution.

RealType n() const;

Returns: The value of the n parameter with which the object was constructed.