--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/ossrv_pub/boost_apis/boost/random/poisson_distribution.hpp Tue Feb 02 02:01:42 2010 +0200
@@ -0,0 +1,99 @@
+/* boost random/poisson_distribution.hpp header file
+ *
+ * Copyright Jens Maurer 2002
+ * 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: poisson_distribution.hpp,v 1.15 2005/05/21 15:57:00 dgregor Exp $
+ *
+ */
+
+#ifndef BOOST_RANDOM_POISSON_DISTRIBUTION_HPP
+#define BOOST_RANDOM_POISSON_DISTRIBUTION_HPP
+
+#include <cmath>
+#include <cassert>
+#include <iostream>
+#include <boost/limits.hpp>
+#include <boost/static_assert.hpp>
+
+namespace boost {
+
+// Knuth
+template<class IntType = int, class RealType = double>
+class poisson_distribution
+{
+public:
+ typedef RealType input_type;
+ typedef IntType result_type;
+
+ explicit poisson_distribution(const RealType& mean = RealType(1))
+ : _mean(mean)
+ {
+#ifndef BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS
+ // MSVC fails BOOST_STATIC_ASSERT with std::numeric_limits at class scope
+ BOOST_STATIC_ASSERT(std::numeric_limits<IntType>::is_integer);
+ BOOST_STATIC_ASSERT(!std::numeric_limits<RealType>::is_integer);
+#endif
+
+ assert(mean > RealType(0));
+ init();
+ }
+
+ // compiler-generated copy ctor and assignment operator are fine
+
+ RealType mean() const { return _mean; }
+ void reset() { }
+
+ template<class Engine>
+ result_type operator()(Engine& eng)
+ {
+ // TODO: This is O(_mean), but it should be O(log(_mean)) for large _mean
+ RealType product = RealType(1);
+ for(result_type m = 0; ; ++m) {
+ product *= eng();
+ if(product <= _exp_mean)
+ return m;
+ }
+ }
+
+#if !defined(BOOST_NO_OPERATORS_IN_NAMESPACE) && !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
+ template<class CharT, class Traits>
+ friend std::basic_ostream<CharT,Traits>&
+ operator<<(std::basic_ostream<CharT,Traits>& os, const poisson_distribution& pd)
+ {
+ os << pd._mean;
+ return os;
+ }
+
+ template<class CharT, class Traits>
+ friend std::basic_istream<CharT,Traits>&
+ operator>>(std::basic_istream<CharT,Traits>& is, poisson_distribution& pd)
+ {
+ is >> std::ws >> pd._mean;
+ pd.init();
+ return is;
+ }
+#endif
+
+private:
+ void init()
+ {
+#ifndef BOOST_NO_STDC_NAMESPACE
+ // allow for Koenig lookup
+ using std::exp;
+#endif
+ _exp_mean = exp(-_mean);
+ }
+
+ RealType _mean;
+ // some precomputed data from the parameters
+ RealType _exp_mean;
+};
+
+} // namespace boost
+
+#endif // BOOST_RANDOM_POISSON_DISTRIBUTION_HPP