90 lines
2.6 KiB
C++
Executable File
90 lines
2.6 KiB
C++
Executable File
/* boost random/cauchy_distribution.hpp header file
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*
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* Copyright Jens Maurer 2000-2001
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* Distributed under the Boost Software License, Version 1.0. (See
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* accompanying file LICENSE_1_0.txt or copy at
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* http://www.boost.org/LICENSE_1_0.txt)
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*
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* See http://www.boost.org for most recent version including documentation.
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*
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* $Id: cauchy_distribution.hpp 41369 2007-11-25 18:07:19Z bemandawes $
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*
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* Revision history
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* 2001-02-18 moved to individual header files
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*/
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#ifndef BOOST_RANDOM_CAUCHY_DISTRIBUTION_HPP
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#define BOOST_RANDOM_CAUCHY_DISTRIBUTION_HPP
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#include <cmath>
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#include <iostream>
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#include <boost/limits.hpp>
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#include <boost/static_assert.hpp>
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namespace boost {
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#if defined(__GNUC__) && (__GNUC__ < 3)
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// Special gcc workaround: gcc 2.95.x ignores using-declarations
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// in template classes (confirmed by gcc author Martin v. Loewis)
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using std::tan;
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#endif
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// Cauchy distribution: p(x) = sigma/(pi*(sigma**2 + (x-median)**2))
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template<class RealType = double>
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class cauchy_distribution
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{
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public:
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typedef RealType input_type;
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typedef RealType result_type;
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#ifndef BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS
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BOOST_STATIC_ASSERT(!std::numeric_limits<RealType>::is_integer);
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#endif
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explicit cauchy_distribution(result_type median_arg = result_type(0),
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result_type sigma_arg = result_type(1))
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: _median(median_arg), _sigma(sigma_arg) { }
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// compiler-generated copy ctor and assignment operator are fine
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result_type median() const { return _median; }
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result_type sigma() const { return _sigma; }
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void reset() { }
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template<class Engine>
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result_type operator()(Engine& eng)
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{
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// Can we have a boost::mathconst please?
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const result_type pi = result_type(3.14159265358979323846);
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#ifndef BOOST_NO_STDC_NAMESPACE
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using std::tan;
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#endif
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return _median + _sigma * tan(pi*(eng()-result_type(0.5)));
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}
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#if !defined(BOOST_NO_OPERATORS_IN_NAMESPACE) && !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
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template<class CharT, class Traits>
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friend std::basic_ostream<CharT,Traits>&
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operator<<(std::basic_ostream<CharT,Traits>& os, const cauchy_distribution& cd)
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{
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os << cd._median << " " << cd._sigma;
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return os;
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}
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template<class CharT, class Traits>
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friend std::basic_istream<CharT,Traits>&
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operator>>(std::basic_istream<CharT,Traits>& is, cauchy_distribution& cd)
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{
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is >> std::ws >> cd._median >> std::ws >> cd._sigma;
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return is;
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}
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#endif
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private:
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result_type _median, _sigma;
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};
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} // namespace boost
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#endif // BOOST_RANDOM_CAUCHY_DISTRIBUTION_HPP
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