/*
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    R E A L    R A N D O M

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*/

    /********************************************************************
     * 
     *   Park, S.K. and Miller, K.W., 1988, "Random Number Generators:
     *   Good Ones are Hard to Find", Communications of the ACM, Vol 31, 
     *   No 10, pp.1192-1201.
     * 
     *  Adapted by John Walker 
     *      Converted to Class Functions -> Octogre 1997
     *      ALife class version -> February 1998
     *      Copyright (c) John F. Walker 1997
     *
     *******************************************************************/
        /*  ---RAW CODE---
         *		extern double seed;
         *		
         *		#define A 16807.0
         *		#define M 2147483647.0
         *		#define Q 127773.0
         *		#define R 2836.0
         *		
         *		double random()
         *		{
         *		  int hi;
         *		  double rand;
         *		  double lo,test;
         *		  hi = seed/Q;
         *		  lo = seed-Q*hi;
         *		  test = A*lo - R*hi;
         *		  if(test>0.0)
         *		    seed = test;
         *		  else
         *		    seed = test + M;
         *		  rand = seed/M;
         *		  return(rand);
         *		}
         */
    
    
    /********************************************************************
     * 
     *  I N S T R U C T I O N S    -->  realRandomJW.h
     * 
     *  If you chose not to read the instructions you are doomed:
     *    DELETE THIS FILE NOW AND FORGET YOU EVER SAW IT.
     * 
     ********************************************************************
     * 
     *  To use these functions, include this header file into 
     *    all the files containing functions which will be calling them.
     *    (I recommend including it everywhere to be sure...) and compiling
     *    the RealRandomJW.cxx file as part of your project.  (Yes, this 
     *    could easily be made into a library.)
     *
     *    Remember to call the SeedRealRandom or TimeSeedRealRandom 
     *    function before calling anything else.  This is NOT checked 
     *    for since it would hurt performance.
     * 
     *    The functions maintain an internal, consistent seed so any
     *    and all functions will not get repeating values.  Only the
     *    inital seed declaration is needed to maintain randomness.
     * 
     * 
     *  SeedRealRandom( double `seed', void | int )
     *      Provide the seed value for the randomization function.
     *
     *  TimeSeedRealRandom( void | int )
     *      Randomly generate the seed value for the randomization function.
     *      This returns the seed generated.
     *
     *     >>>  ONE OF THE ABOVE IS REQUIRED          <<<
     *     >>>    BEFORE CALLING ANY OTHER FUNCTION ! <<<
     *
     *  GetRealRandomSeed( double `seed' )
     *      Returns the (double) value of the current seed state.
     *
     *  RealRandom( void )
     *      Returns a double value between 0.0 and .9999999999999999
     *                                               (not a joke)
     *
     *  RealRandomDouble( double maximum )
     *      Returns a double value between 0.0 and 
     *                                     maximum*.9999999999999999
     *      `maximum' will never be returned, ever.
     *
     *  RealRandomFloat( float maximum )
     *      As above only returns a float
     *
     *  RealRandomInt( integer maximum )
     *      Returns an integer value from 0 to (maximum-1).
     *      Again, the value `maximum' will NEVER be returned.
     *
     *  GetM_CNST(void)
     *      This function returns the value of the `M constant' used
     *      by real_random.  This is provided primarily for creative
     *      seed generation and is not needed for normal use.
     *
     *
     *  private functions:
     *
     *      RealRandomCycle( void | int cycleNumber)
     *          Repeatedly calls the RealRandomJW function to cycle the
     *          generator and get it out of repeat cycles caused by 
     *          numerically similar seeds.  The defualt cycle is defined,
     *          but this can be changed with the `cycleNumber' parameter.
     *          If cycleNumber = 0, then the default value is used.
     * 
     ********************************************************************
     *
     *  This code is not intended for distribution.  If you chose to use
     *    it,  please give approprite credit to Park and Miller as
     *    the creators of the algorithm.
     *
     ********************************************************************/
    
    
#ifndef __REAL_RANDOM_JW__
    #define __REAL_RANDOM_JW__ 1
    
    #include <stdio.h>
    #include <time.h>
    

    class CRealRandomJW  
    {
        public:
            CRealRandomJW();
            virtual ~CRealRandomJW();

            void   SeedRealRandom(double);
            void   SeedRealRandom(double,int);
            double TimeSeedRealRandom(void);
            double TimeSeedRealRandom(int);
            double GetRealRandomSeed(void);
            double RealRandom(void);
            double RealRandomDouble(double);
            float  RealRandomFloat(float);
            int    RealRandomInt(int);

            double GetM_CNST(void);

        private:
            double jwRealRandomSeed;
            void   RealRandomCycle(void);
            void   RealRandomCycle(int);
    };

#endif /* __REAL_RANDOM_JW__ */



/*
//  $Author: volker $
//  $Revision: 1.0 $
//  $Date: 1995/11/04 17:29:47 $
//
//  (C) 1997 John Franklin Walker
*/