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// Copyright (c) 1997-2001 Utrecht University (The Netherlands),
// ETH Zurich (Switzerland), Freie Universitaet Berlin (Germany),
// INRIA Sophia-Antipolis (France), Martin-Luther-University Halle-Wittenberg
// (Germany), Max-Planck-Institute Saarbruecken (Germany), RISC Linz (Austria),
// and Tel-Aviv University (Israel). All rights reserved.
//
// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; version 2.1 of the License.
// See the file LICENSE.LGPL distributed with CGAL.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL: svn+ssh://scm.gforge.inria.fr/svn/cgal/branches/CGAL-3.5-branch/Random_numbers/include/CGAL/Random.h $
// $Id: Random.h 46871 2008-11-13 14:40:48Z gaertner $
//
//
// Author(s) : Sven Schoenherr <sven@inf.ethz.ch>, Sylvain Pion
#ifndef CGAL_RANDOM_H
#define CGAL_RANDOM_H
#include <utility>
#include <CGAL/basic.h>
CGAL_BEGIN_NAMESPACE
class Random {
public:
// types
typedef std::pair<unsigned int, unsigned int> State;
// creation
Random( );
Random( unsigned int seed);
// seed
unsigned int get_seed ( ) const;
// operations
bool get_bool ( );
int get_int ( int lower, int upper);
double get_double( double lower = 0.0, double upper = 1.0);
// state
void save_state( State& state) const;
void restore_state( const State& state);
// Computes a random int value smaller than 2^b.
// It's supposed to be fast, useful for randomized algorithms.
// The distribution is not perfectly flat, but this is a sacrifice against
// efficiency.
template <int b>
int get_bits()
{
CGAL_assertion(0<b && b<16);
if (val == 0) {
random_value = (421U * random_value + 2073U) % 32749U;
val = random_value;
}
int ret = val & ((1<<b)-1);
val >>= 1; // Shifting by b would be slightly better, but is slower.
return ret;
}
int operator () ( int upper);
bool operator==(Random rd) const
{
return
rd.rand_max_plus_1 == rand_max_plus_1 &&
rd.random_value == random_value &&
rd.val == val;
}
private:
// data members
const double rand_max_plus_1;
unsigned int random_value; // Current 15 bits random value.
unsigned int val; // random_value shifted by used bits.
unsigned int seed;
};
// Global variables
// ================
extern Random default_random;
CGAL_END_NAMESPACE
// ============================================================================
// Class implementation (inline functions)
// =======================================
// includes
# include <cstdlib>
CGAL_BEGIN_NAMESPACE
// operations
inline
bool
Random::
get_bool( )
{
return( static_cast< bool>( std::rand() & 1));
}
inline
int
Random::
get_int( int lower, int upper)
{
return( lower + static_cast< int>(
( static_cast< double>( upper) - lower) *
std::rand() / rand_max_plus_1));
}
inline
double
Random::
get_double( double lower, double upper)
{
return( lower + ( ( upper-lower) *
std::rand() / rand_max_plus_1));
}
inline
int
Random::
operator () ( int upper)
{
return( get_int( 0, upper));
}
CGAL_END_NAMESPACE
#endif // CGAL_RANDOM_H
// ===== EOF ==================================================================
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