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## Class template piecewise_linear_distribution

boost::random::piecewise_linear_distribution

## Synopsis

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

    template<typename RealType = double>
    class piecewise_linear_distribution {
    public:
      // types
      typedef std::size_t input_type;
      typedef RealType    result_type;

      // member classes/structs/unions

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

        // construct/copy/destruct
        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);

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

        // public member functions
        std::vector< RealType > intervals() const;
        std::vector< RealType > densities() const;
      };

      // construct/copy/destruct
      piecewise_linear_distribution();
      template<typename IntervalIter, typename WeightIter>
        piecewise_linear_distribution(IntervalIter, IntervalIter, WeightIter);
      template<typename T, typename F>
        piecewise_linear_distribution(std::initializer_list< T >, F);
      template<typename IntervalsRange, typename WeightsRange>
        piecewise_linear_distribution(const IntervalsRange &,
                                      const WeightsRange &);
      template<typename F>
        piecewise_linear_distribution(std::size_t, RealType, RealType, F);
      explicit piecewise_linear_distribution(const param_type &);

      // public member functions
      template<typename URNG> RealType operator()(URNG &) const;
      template<typename URNG>
        RealType operator()(URNG &, const param_type &) const;
      result_type min() const;
      result_type max() const;
      std::vector< RealType > densities() const;
      std::vector< RealType > intervals() const;
      param_type param() const;
      void param(const param_type &);
      void reset();

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

## Description

The class `piecewise_linear_distribution` models a random distribution .

### `piecewise_linear_distribution` public construct/copy/destruct

1.     piecewise_linear_distribution();

   Creates a new ``piecewise_linear_distribution`` that produces values uniformly distributed in the range [0, 1).

2.     template<typename IntervalIter, typename WeightIter>
         piecewise_linear_distribution(IntervalIter first_interval,
                                       IntervalIter last_interval,
                                       WeightIter first_weight);

   Constructs a `piecewise_linear_distribution` from two iterator ranges containing the interval boundaries and the weights at the boundaries. If there are fewer than two boundaries, then this is equivalent to the default constructor and creates a distribution that produces values uniformly distributed in the range [0, 1).

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

   For example,

       double intervals[] = { 0.0, 1.0, 2.0 };
       double weights[] = { 0.0, 1.0, 0.0 };
       piecewise_constant_distribution<> dist(
           &intervals[0], &intervals[0] + 3, &weights[0]);

   produces a triangle distribution.

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

   Constructs a `piecewise_linear_distribution` 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 corresponding interval boundary.

   If the initializer_list contains fewer 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 IntervalsRange, typename WeightsRange>
         piecewise_linear_distribution(const IntervalsRange & intervals_arg,
                                       const WeightsRange & weights_arg);

   Constructs a `piecewise_linear_distribution` from Boost.Range ranges holding the interval boundaries and the weights. If there are fewer 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 equal to the number of interval boundaries.

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

   Constructs a `piecewise_linear_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 interval boundaries.

6.     explicit piecewise_linear_distribution(const param_type & param);

   Constructs a `piecewise_linear_distribution` from its parameters.

### `piecewise_linear_distribution` public member functions

1.     template<typename URNG> RealType operator()(URNG & urng) const;

   Returns a value distributed according to the parameters of the `piecewise_linear_distribution`.

2.     template<typename URNG>
         RealType operator()(URNG & urng, const param_type & param) const;

   Returns a value distributed according to the parameters specified by param.

3.     result_type min() const;

   Returns the smallest value that the distribution can produce.

4.     result_type max() const;

   Returns the largest value that the distribution can produce.

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

   Returns a vector containing the probability densities at the interval boundaries.

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

   Returns a vector containing the interval boundaries.

7.     param_type param() const;

   Returns the parameters of the distribution.

8.     void param(const param_type & param);

   Sets the parameters of the distribution.

9.     void reset();

   Effects: Subsequent uses of the distribution do not depend on values produced by any engine prior to invoking reset.

### `piecewise_linear_distribution` friend functions

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

   Writes a distribution to a `std::ostream`.

2.     template<typename CharT, typename Traits>
         friend std::basic_istream< CharT, Traits > &
         operator>>(std::basic_istream< CharT, Traits > & is,
                    const piecewise_linear_distribution & pld);

   Reads a distribution from a `std::istream`

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

   Returns true if the two distributions will return the same sequence of values, when passed equal generators.

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

   Returns true if the two distributions may return different sequences of values, when passed equal generators.