--- /dev/null
+/* boost random/extreme_value_distribution.hpp header file
+ *
+ * Copyright Steven Watanabe 2010
+ * 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: extreme_value_distribution.hpp 71018 2011-04-05 21:27:52Z steven_watanabe $
+ */
+
+#ifndef BOOST_RANDOM_EXTREME_VALUE_DISTRIBUTION_HPP
+#define BOOST_RANDOM_EXTREME_VALUE_DISTRIBUTION_HPP
+
+#include <boost/config/no_tr1/cmath.hpp>
+#include <iosfwd>
+#include <istream>
+#include <boost/config.hpp>
+#include <boost/limits.hpp>
+#include <boost/random/detail/operators.hpp>
+#include <boost/random/uniform_01.hpp>
+
+namespace boost {
+namespace random {
+
+/**
+ * The extreme value distribution is a real valued distribution with two
+ * parameters a and b.
+ *
+ * It has \f$\displaystyle p(x) = \frac{1}{b}e^{\frac{a-x}{b} - e^\frac{a-x}{b}}\f$.
+ */
+template<class RealType = double>
+class extreme_value_distribution {
+public:
+ typedef RealType result_type;
+ typedef RealType input_type;
+
+ class param_type {
+ public:
+ typedef extreme_value_distribution distribution_type;
+
+ /**
+ * Constructs a @c param_type from the "a" and "b" parameters
+ * of the distribution.
+ *
+ * Requires: b > 0
+ */
+ explicit param_type(RealType a_arg = 1.0, RealType b_arg = 1.0)
+ : _a(a_arg), _b(b_arg)
+ {}
+
+ /** Returns the "a" parameter of the distribtuion. */
+ RealType a() const { return _a; }
+ /** Returns the "b" parameter of the distribution. */
+ RealType b() const { return _b; }
+
+ /** Writes a @c param_type to a @c std::ostream. */
+ BOOST_RANDOM_DETAIL_OSTREAM_OPERATOR(os, param_type, parm)
+ { os << parm._a << ' ' << parm._b; return os; }
+
+ /** Reads a @c param_type from a @c std::istream. */
+ BOOST_RANDOM_DETAIL_ISTREAM_OPERATOR(is, param_type, parm)
+ { is >> parm._a >> std::ws >> parm._b; return is; }
+
+ /** Returns true if the two sets of parameters are the same. */
+ BOOST_RANDOM_DETAIL_EQUALITY_OPERATOR(param_type, lhs, rhs)
+ { return lhs._a == rhs._a && lhs._b == rhs._b; }
+
+ /** Returns true if the two sets of parameters are the different. */
+ BOOST_RANDOM_DETAIL_INEQUALITY_OPERATOR(param_type)
+
+ private:
+ RealType _a;
+ RealType _b;
+ };
+
+ /**
+ * Constructs an @c extreme_value_distribution from its "a" and "b" parameters.
+ *
+ * Requires: b > 0
+ */
+ explicit extreme_value_distribution(RealType a_arg = 1.0, RealType b_arg = 1.0)
+ : _a(a_arg), _b(b_arg)
+ {}
+ /** Constructs an @c extreme_value_distribution from its parameters. */
+ explicit extreme_value_distribution(const param_type& parm)
+ : _a(parm.a()), _b(parm.b())
+ {}
+
+ /**
+ * Returns a random variate distributed according to the
+ * @c extreme_value_distribution.
+ */
+ template<class URNG>
+ RealType operator()(URNG& urng) const
+ {
+ using std::log;
+ return _a - log(-log(uniform_01<RealType>()(urng))) * _b;
+ }
+
+ /**
+ * Returns a random variate distributed accordint to the extreme
+ * value distribution with parameters specified by @c param.
+ */
+ template<class URNG>
+ RealType operator()(URNG& urng, const param_type& parm) const
+ {
+ return extreme_value_distribution(parm)(urng);
+ }
+
+ /** Returns the "a" parameter of the distribution. */
+ RealType a() const { return _a; }
+ /** Returns the "b" parameter of the distribution. */
+ RealType b() const { return _b; }
+
+ /** Returns the smallest value that the distribution can produce. */
+ RealType min BOOST_PREVENT_MACRO_SUBSTITUTION () const
+ { return -std::numeric_limits<RealType>::infinity(); }
+ /** Returns the largest value that the distribution can produce. */
+ RealType max BOOST_PREVENT_MACRO_SUBSTITUTION () const
+ { return std::numeric_limits<RealType>::infinity(); }
+
+ /** Returns the parameters of the distribution. */
+ param_type param() const { return param_type(_a, _b); }
+ /** Sets the parameters of the distribution. */
+ void param(const param_type& parm)
+ {
+ _a = parm.a();
+ _b = parm.b();
+ }
+
+ /**
+ * Effects: Subsequent uses of the distribution do not depend
+ * on values produced by any engine prior to invoking reset.
+ */
+ void reset() { }
+
+ /** Writes an @c extreme_value_distribution to a @c std::ostream. */
+ BOOST_RANDOM_DETAIL_OSTREAM_OPERATOR(os, extreme_value_distribution, wd)
+ {
+ os << wd.param();
+ return os;
+ }
+
+ /** Reads an @c extreme_value_distribution from a @c std::istream. */
+ BOOST_RANDOM_DETAIL_ISTREAM_OPERATOR(is, extreme_value_distribution, wd)
+ {
+ param_type parm;
+ if(is >> parm) {
+ wd.param(parm);
+ }
+ return is;
+ }
+
+ /**
+ * Returns true if the two instances of @c extreme_value_distribution will
+ * return identical sequences of values given equal generators.
+ */
+ BOOST_RANDOM_DETAIL_EQUALITY_OPERATOR(extreme_value_distribution, lhs, rhs)
+ { return lhs._a == rhs._a && lhs._b == rhs._b; }
+
+ /**
+ * Returns true if the two instances of @c extreme_value_distribution will
+ * return different sequences of values given equal generators.
+ */
+ BOOST_RANDOM_DETAIL_INEQUALITY_OPERATOR(extreme_value_distribution)
+
+private:
+ RealType _a;
+ RealType _b;
+};
+
+} // namespace random
+} // namespace boost
+
+#endif // BOOST_RANDOM_EXTREME_VALUE_DISTRIBUTION_HPP