comparison DEPENDENCIES/generic/include/boost/random/geometric_distribution.hpp @ 16:2665513ce2d3

Add boost headers

+/* boost random/geometric_distribution.hpp header file
+ *
+ * Copyright Jens Maurer 2000-2001
+ * Copyright Steven Watanabe 2011
+ * Distributed under the Boost Software License, Version 1.0. (See
+ * accompanying file LICENSE_1_0.txt or copy at
+ * http://www.boost.org/LICENSE_1_0.txt)
+ *
+ * See http://www.boost.org for most recent version including documentation.
+ *
+ * $Id: geometric_distribution.hpp 74867 2011-10-09 23:13:31Z steven_watanabe $
+ *
+ * Revision history
+ *  2001-02-18  moved to individual header files
+ */
+
+#ifndef BOOST_RANDOM_GEOMETRIC_DISTRIBUTION_HPP
+#define BOOST_RANDOM_GEOMETRIC_DISTRIBUTION_HPP
+
+#include <boost/config/no_tr1/cmath.hpp>          // std::log
+#include <iosfwd>
+#include <ios>
+#include <boost/assert.hpp>
+#include <boost/random/detail/config.hpp>
+#include <boost/random/detail/operators.hpp>
+#include <boost/random/uniform_01.hpp>
+
+namespace boost {
+namespace random {
+
+/**
+ * An instantiation of the class template @c geometric_distribution models
+ * a \random_distribution.  The distribution produces positive
+ * integers which are the number of bernoulli trials
+ * with probability @c p required to get one that fails.
+ *
+ * For the geometric distribution, \f$p(i) = p(1-p)^{i}\f$.
+ *
+ * @xmlwarning
+ * This distribution has been updated to match the C++ standard.
+ * Its behavior has changed from the original
+ * boost::geometric_distribution.  A backwards compatible
+ * wrapper is provided in namespace boost.
+ * @endxmlwarning
+ */
+template<class IntType = int, class RealType = double>
+class geometric_distribution
+{
+public:
+    typedef RealType input_type;
+    typedef IntType result_type;
+
+    class param_type
+    {
+    public:
+
+        typedef geometric_distribution distribution_type;
+
+        /** Constructs the parameters with p. */
+        explicit param_type(RealType p_arg = RealType(0.5))
+          : _p(p_arg)
+        {
+            BOOST_ASSERT(RealType(0) < _p && _p < RealType(1));
+        }
+
+        /** Returns the p parameter of the distribution. */
+        RealType p() const { return _p; }
+
+        /** Writes the parameters to a std::ostream. */
+        BOOST_RANDOM_DETAIL_OSTREAM_OPERATOR(os, param_type, parm)
+        {
+            os << parm._p;
+            return os;
+        }
+
+        /** Reads the parameters from a std::istream. */
+        BOOST_RANDOM_DETAIL_ISTREAM_OPERATOR(is, param_type, parm)
+        {
+            double p_in;
+            if(is >> p_in) {
+                if(p_in > RealType(0) && p_in < RealType(1)) {
+                    parm._p = p_in;
+                } else {
+                    is.setstate(std::ios_base::failbit);
+                }
+            }
+            return is;
+        }
+
+        /** Returns true if the two sets of parameters are equal. */
+        BOOST_RANDOM_DETAIL_EQUALITY_OPERATOR(param_type, lhs, rhs)
+        { return lhs._p == rhs._p; }
+
+        /** Returns true if the two sets of parameters are different. */
+        BOOST_RANDOM_DETAIL_INEQUALITY_OPERATOR(param_type)
+
+
+    private:
+        RealType _p;
+    };
+
+    /**
+     * Contructs a new geometric_distribution with the paramter @c p.
+     *
+     * Requires: 0 < p < 1
+     */
+    explicit geometric_distribution(const RealType& p = RealType(0.5))
+      : _p(p)
+    {
+        BOOST_ASSERT(RealType(0) < _p && _p < RealType(1));
+        init();
+    }
+
+    /** Constructs a new geometric_distribution from its parameters. */
+    explicit geometric_distribution(const param_type& parm)
+      : _p(parm.p())
+    {
+        init();
+    }
+
+    // compiler-generated copy ctor and assignment operator are fine
+
+    /** Returns: the distribution parameter @c p  */
+    RealType p() const { return _p; }
+
+    /** Returns the smallest value that the distribution can produce. */
+    IntType min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return IntType(0); }
+
+    /** Returns the largest value that the distribution can produce. */
+    IntType max BOOST_PREVENT_MACRO_SUBSTITUTION () const
+    { return (std::numeric_limits<IntType>::max)(); }
+
+    /** Returns the parameters of the distribution. */
+    param_type param() const { return param_type(_p); }
+
+    /** Sets the parameters of the distribution. */
+    void param(const param_type& parm)
+    {
+        _p = parm.p();
+        init();
+    }
+  
+    /**
+     * Effects: Subsequent uses of the distribution do not depend
+     * on values produced by any engine prior to invoking reset.
+     */
+    void reset() { }
+
+    /**
+     * Returns a random variate distributed according to the
+     * geometric_distribution.
+     */
+    template<class Engine>
+    result_type operator()(Engine& eng) const
+    {
+        using std::log;
+        using std::floor;
+        RealType x = RealType(1) - boost::uniform_01<RealType>()(eng);
+        return IntType(floor(log(x) / _log_1mp));
+    }
+
+    /**
+     * Returns a random variate distributed according to the
+     * geometric distribution with parameters specified by param.
+     */
+    template<class Engine>
+    result_type operator()(Engine& eng, const param_type& parm) const
+    { return geometric_distribution(parm)(eng); }
+
+    /** Writes the distribution to a @c std::ostream. */
+    BOOST_RANDOM_DETAIL_OSTREAM_OPERATOR(os, geometric_distribution, gd)
+    {
+        os << gd._p;
+        return os;
+    }
+
+    /** Reads the distribution from a @c std::istream. */
+    BOOST_RANDOM_DETAIL_ISTREAM_OPERATOR(is, geometric_distribution, gd)
+    {
+        param_type parm;
+        if(is >> parm) {
+            gd.param(parm);
+        }
+        return is;
+    }
+
+    /**
+     * Returns true if the two distributions will produce identical
+     * sequences of values given equal generators.
+     */
+    BOOST_RANDOM_DETAIL_EQUALITY_OPERATOR(geometric_distribution, lhs, rhs)
+    { return lhs._p == rhs._p; }
+
+    /**
+     * Returns true if the two distributions may produce different
+     * sequences of values given equal generators.
+     */
+    BOOST_RANDOM_DETAIL_INEQUALITY_OPERATOR(geometric_distribution)
+
+private:
+
+    /// \cond show_private
+
+    void init()
+    {
+        using std::log;
+        _log_1mp = log(1 - _p);
+    }
+
+    RealType _p;
+    RealType _log_1mp;
+
+    /// \endcond
+};
+
+} // namespace random
+
+/// \cond show_deprecated
+
+/**
+ * Provided for backwards compatibility.  This class is
+ * deprecated.  It provides the old behavior of geometric_distribution
+ * with \f$p(i) = (1-p) p^{i-1}\f$.
+ */
+template<class IntType = int, class RealType = double>
+class geometric_distribution
+{
+public:
+    typedef RealType input_type;
+    typedef IntType result_type;
+
+    explicit geometric_distribution(RealType p_arg = RealType(0.5))
+      : _impl(1 - p_arg) {}
+
+    RealType p() const { return 1 - _impl.p(); }
+
+    void reset() {}
+
+    template<class Engine>
+    IntType operator()(Engine& eng) const { return _impl(eng) + IntType(1); }
+
+    BOOST_RANDOM_DETAIL_OSTREAM_OPERATOR(os, geometric_distribution, gd)
+    {
+        os << gd.p();
+        return os;
+    }
+
+    BOOST_RANDOM_DETAIL_ISTREAM_OPERATOR(is, geometric_distribution, gd)
+    {
+        RealType val;
+        if(is >> val) {
+            typename impl_type::param_type impl_param(1 - val);
+            gd._impl.param(impl_param);
+        }
+        return is;
+    }
+
+private:
+    typedef random::geometric_distribution<IntType, RealType> impl_type;
+    impl_type _impl;
+};
+
+/// \endcond
+
+} // namespace boost
+
+#endif // BOOST_RANDOM_GEOMETRIC_DISTRIBUTION_HPP