| Home | Libraries | People | FAQ | More

## Class param_type

boost::random::piecewise_constant_distribution::param_type

## Synopsis

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

    class param_type {
    public:
      // types
      typedef piecewise_constant_distribution distribution_type;

      // friend functions
      template<typename CharT, typename Traits>
        std::basic_ostream< CharT, Traits > &
        operator<<(std::basic_ostream< CharT, Traits > &, const param_type &);
      template<typename CharT, typename Traits>
        std::basic_istream< CharT, Traits > &
        operator>>(std::basic_istream< CharT, Traits > &, const param_type &);
      bool operator==(const param_type &, const param_type &);
      bool operator!=(const param_type &, const param_type &);

      // public member functions
      param_type();
      template<typename IntervalIter, typename WeightIter>
        param_type(IntervalIter, IntervalIter, WeightIter);
      template<typename T, typename F>
        param_type(const std::initializer_list< T > &, F);
      template<typename IntervalRange, typename WeightRange>
        param_type(const IntervalRange &, const WeightRange &);
      template<typename F> param_type(std::size_t, RealType, RealType, F);
      std::vector< RealType > intervals() const;
      std::vector< RealType > densities() const;
    };

## Description

### `param_type` friend functions

1.     template<typename CharT, typename Traits>
         std::basic_ostream< CharT, Traits > &
         operator<<(std::basic_ostream< CharT, Traits > & os,
                    const param_type & param);

   Writes the parameters to a `std::ostream`.

2.     template<typename CharT, typename Traits>
         std::basic_istream< CharT, Traits > &
         operator>>(std::basic_istream< CharT, Traits > & is,
                    const param_type & param);

   Reads the parameters from a `std::istream`.

3.     bool operator==(const param_type & lhs, const param_type & rhs);

   Returns true if the two sets of parameters are the same.

4.     bool operator!=(const param_type & lhs, const param_type & rhs);

   Returns true if the two sets of parameters are different.

### `param_type` public member functions

1.     param_type();

   Constructs a `param_type` object, representing a distribution that produces values uniformly distributed in the range [0, 1).

2.     template<typename IntervalIter, typename WeightIter>
         param_type(IntervalIter intervals_first, IntervalIter intervals_last,
                    WeightIter weight_first);

   Constructs a `param_type` object from two iterator ranges containing the interval boundaries and the interval weights. If there are less than two boundaries, then this is equivalent to the default constructor and creates a single interval, [0, 1).

   The values of the interval boundaries must be strictly increasing, and the number of weights must be one less than the number of interval boundaries. If there are extra weights, they are ignored.

3.     template<typename T, typename F>
         param_type(const std::initializer_list< T > & il, F f);

   Constructs a `param_type` object from an initializer_list containing the interval boundaries and a unary function specifying the weights. Each weight is determined by calling the function at the midpoint of the corresponding interval.

   If the initializer_list contains less than two elements, this is equivalent to the default constructor and the distribution will produce values uniformly distributed in the range [0, 1).

4.     template<typename IntervalRange, typename WeightRange>
         param_type(const IntervalRange & intervals_arg,
                    const WeightRange & weights_arg);

   Constructs a `param_type` object from Boost.Range ranges holding the interval boundaries and the weights. If there are less than two interval boundaries, this is equivalent to the default constructor and the distribution will produce values uniformly distributed in the range [0, 1). The number of weights must be one less than the number of interval boundaries.

5.     template<typename F>
         param_type(std::size_t nw, RealType xmin, RealType xmax, F f);

   Constructs the parameters for a distribution that approximates a function. The range of the distribution is [xmin, xmax). This range is divided into nw equally sized intervals and the weights are found by calling the unary function f on the midpoints of the intervals.

6.     std::vector< RealType > intervals() const;

   Returns a vector containing the interval boundaries.

7.     std::vector< RealType > densities() const;

   Returns a vector containing the probability densities over all the intervals of the distribution.