mirror of https://github.com/CGAL/cgal
164 lines
4.0 KiB
C++
164 lines
4.0 KiB
C++
// Copyright (c) 1997-2001 Utrecht University (The Netherlands),
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// ETH Zurich (Switzerland), Freie Universitaet Berlin (Germany),
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// INRIA Sophia-Antipolis (France), Martin-Luther-University Halle-Wittenberg
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// (Germany), Max-Planck-Institute Saarbruecken (Germany), RISC Linz (Austria),
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// and Tel-Aviv University (Israel). All rights reserved.
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//
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// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public License as
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// published by the Free Software Foundation; version 2.1 of the License.
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// See the file LICENSE.LGPL distributed with CGAL.
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//
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// Licensees holding a valid commercial license may use this file in
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// accordance with the commercial license agreement provided with the software.
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//
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// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
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// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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//
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// $URL$
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// $Id$
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//
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//
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// Author(s) : Sven Schoenherr <sven@inf.ethz.ch>, Sylvain Pion, Andreas Fabri
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#ifndef CGAL_RANDOM_H
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#define CGAL_RANDOM_H
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#include <string>
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#include <utility>
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#include <CGAL/basic.h>
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#include <boost/random/linear_congruential.hpp>
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#include <boost/random/uniform_int.hpp>
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#include <boost/random/uniform_real.hpp>
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#include <boost/random/variate_generator.hpp>
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namespace CGAL {
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class Random {
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public:
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// types
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struct State {
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std::string rng;
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unsigned int random_value, val, seed;
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State()
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{}
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State(std::string rng,
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unsigned int random_value,
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unsigned int val,
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unsigned int seed)
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: rng(rng), random_value(random_value), val(val), seed(seed)
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{}
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};
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// creation
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Random( );
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Random( unsigned int seed);
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// seed
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unsigned int get_seed ( ) const;
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// operations
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bool get_bool( )
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{
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return( static_cast< bool>( rng() & 1));
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}
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template <typename IntType>
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IntType
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get_int(IntType lower, IntType upper)
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{
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// uniform_int has a closed interval, CGAL a halfopen
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boost::uniform_int<IntType> dist(lower,upper-1);
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boost::variate_generator<boost::rand48&, boost::uniform_int<IntType> > generator(rng,dist);
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return generator();
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}
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template <typename IntType>
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IntType operator () (IntType upper)
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{
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return( get_int( IntType(0), upper));
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}
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template <typename RealType>
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RealType
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get_double( RealType lower, RealType upper)
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{
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// uniform_real as well as CGAL have a halfopen interval
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boost::uniform_real<RealType> dist(lower,upper);
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boost::variate_generator<boost::rand48&, boost::uniform_real<RealType> > generator(rng,dist);
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return generator();
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}
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template <typename RealType>
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RealType
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get_double( RealType lower)
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{
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return get_double<RealType>(lower, RealType(1.0));
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}
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double
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get_double()
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{
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return get_double<double>(0.0,1.0);
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}
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// state
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void save_state( State& state) const;
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void restore_state( const State& state);
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// Computes a random int value smaller than 2^b.
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// It's supposed to be fast, useful for randomized algorithms.
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// The distribution is not perfectly flat, but this is a sacrifice against
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// efficiency.
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template <int b>
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int get_bits()
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{
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CGAL_assertion(0<b && b<16);
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if (val == 0) {
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random_value = (421U * random_value + 2073U) % 32749U;
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val = random_value;
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}
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int ret = val & ((1<<b)-1);
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val >>= 1; // Shifting by b would be slightly better, but is slower.
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return ret;
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}
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bool operator==(Random rd) const
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{
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return (rng == rd.rng)
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&& (random_value == rd.random_value)
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&& (val == rd.val)
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&& (seed == rd.seed);
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}
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private:
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// data members
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unsigned int random_value; // Current 15 bits random value.
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unsigned int val; // random_value shifted by used bits.
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unsigned int seed;
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boost::rand48 rng;
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};
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// Global variables
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// ================
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extern Random default_random;
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} //namespace CGAL
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#endif // CGAL_RANDOM_H
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