randomnr.cpp

一个用c++编写的多目标遗传算法程序

/*******************************************************************************
	RandomNr.cpp
	
		last change: 01/20/1999
	
		version: 0.0.0
	
		design:	Eckart Zitzler
			Paul E. Sevinc
		
		implementation:	Paul E. Sevinc
	
		(c) 1998-1999:	Computer Engineering and Networks Laboratory
				Swiss Federal Institute of Technology Zurich
	
		description:
			See RandomNr.h
*******************************************************************************/

#include "RandomNr.h"

#include <climits>
#include <cstddef>
#include <ctime>
#include "TIKEAFExceptions.h"

using namespace std;


RandomNr::RandomNr()
{
	z = static_cast< long >( time( 0 ) ); // see <ctime>
}


RandomNr::RandomNr( long seed )
	: z( seed )
{
}


void
RandomNr::setSeed( long seed )
{
	z = seed;
}


double
RandomNr::uniform01()
{
// see Reiser, Martin / Wirth, Niklaus.
//	- Programming in Oberon: Steps beyond Pascal and Modula.

	const int	a = 16807,
			m = LONG_MAX,	// see <climits> - replace by
					// numeric_limits< long >::max()
					// when <limits> is available
			q = m / a,
			r = m % a;

	long	gamma;

	gamma = a * ( z % q ) - r * ( z / q );
	z = ( gamma > 0 ) ? gamma : ( gamma + m );
	return z * ( 1.0 / m );

// NOTE: we're in trouble if at some point z becomes -LONG_MAX, 0, or LONG_MAX...
}


bool
RandomNr::flipP( double p )
	throw ( ProbabilityException )
{
#ifndef NOTIKEAFEXCEPTIONS
	if ( p < 0 || p > 1 )
	{
		throw ProbabilityException( "from RandomNr::flipP" );
	}
#endif

	return uniform01() < p ? true : false;
}


size_t
RandomNr::uniform0Max( size_t max )	// exclusive
	throw ( LimitsException )
{
#ifndef NOTIKEAFEXCEPTIONS
	if ( max == 0 )
	{
		throw LimitsException( "from RandomNr::uniform0Max" );
	}
#endif
	
	return static_cast< size_t >( max * uniform01() );
}


int
RandomNr::uniformMinMax(	int	min,	// inclusive
				int	max )	// exclusive
	throw ( LimitsException )
{
#ifndef NOTIKEAFEXCEPTIONS
	if ( min >= max )
	{
		throw LimitsException( "from RandomNr::uniformMinMax" );
	}
#endif
	
	return min >= 0
		? static_cast< int >( min + ( max - min ) * uniform01() )
		: static_cast< int >( min - 1 + ( max - min ) * uniform01() );
}