// Swarm library. Copyright © 1996-2000 Swarm Development Group.
// This library is distributed without any warranty; without even the
// implied warranty of merchantability or fitness for a particular
// purpose.  See file LICENSE for details and terms of copying.

/*
Name:            ExponentialDist.h
Description:     Exponential distribuiton returning doubles
Library:         random
Original Author: Sven Thommesen
Date:            1997-01-15

Modified by:	 Sven Thommesen
Date:		 1997-09-01 (v. 0.7)
Changes:	 Standardized the informational comments.
		 Eliminated code to generate uniform doubles
		 in favor of calling the generator for this service.
		 Added code to deal with split generators.
		 Added method -createWithDefault.
		 Removed distinction between frozen and non-frozen state.

Modified by:	Sven Thommesen
Date:		1998-10-08 (v. 0.8)
Changes:	Rearranged code for create-phase compatibility.

Modified by:	Sven Thommesen
Date:		2000-02-21 (v. 0.81)
Changes:	Added (id <GeneratorType>) to method definitions.

*/

/*
123456789|123456789|123456789|123456789|123456789|123456789|123456789|123456789|
*/

/*
--------------- | Distribution Documentation:
		| ---------------------------

Name:		| ExponentialDistribution

Description:	| Exponential distribution returning double values

Algorithm:	| Transformation method

Reference:	| Russell 1992

Parameters:	| double Mean

State:		| unsigned long long int currentCount

ExponentialDist	| On a 486/66, the following measures were obtained,
speed:		| using MT19937 as the underlying generator:

		|  -getDoubleSample:                          20.905 uS
		|  -average # of generator calls per variate:  1.000 (D)
		|  -distribution net time:                    10.746 uS

Relative speed:	| Speed 0.177 (time 5.653) relative to MT19937 getUnsignedSample
--------------- . ------------------------------------------------------------- 
*/


#import <objectbase/SwarmObject.h>
#import <random.h>


@interface ExponentialDist: SwarmObject <ExponentialDist>

{

// Distribution personality:

   unsigned 	stateSize;
   unsigned	distMagic;
   char		distName[DISTNAMESIZE];

// Data objects and fixed variables:

   id 		randomGenerator;
   unsigned	generatorMax;

   BOOL		useSplitGenerator;
   unsigned	virtualGenerator;
   BOOL 	optionsInitialized;

// Count of variates generated:

   unsigned long long int currentCount;

// -- 

// Parameters:

   double theMean;

// Working variables:

   // (none)

// State variables:

   // (none)

}

CREATING

// @protocol ExponentialDist <DoubleDistribution, CREATABLE> 

- initState;		// unpublished

+ create      : (id <Zone>)aZone
  setGenerator: (id <SimpleRandomGenerator>) generator
       setMean: (double)mean;

+ create             : (id <Zone>)aZone
         setGenerator: (id <SplitRandomGenerator>) generator
  setVirtualGenerator: (unsigned)vGen
              setMean: (double)mean;

// @protocol DoubleDistribution <ProbabilityDistribution>

// @protocol ProbabilityDistribution <SwarmObject, InternalState> 

+ createWithDefaults: (id <Zone>)aZone;

+ create: (id <Zone>)aZone setGenerator: (id <SimpleRandomGenerator>) generator;

+ create             : (id <Zone>)aZone 
         setGenerator: (id <SplitRandomGenerator>) generator
  setVirtualGenerator: (unsigned) vGen;

+ createBegin: (id <Zone>)aZone;
- createEnd;

// @protocol InternalState

SETTING

// @protocol ExponentialDist <DoubleDistribution, CREATABLE> 
- resetState;		// unpublished
- setMean: (double)mean;

// @protocol BooleanDistribution <ProbabilityDistribution> 

// @protocol ProbabilityDistribution <SwarmObject, InternalState> 
- setGenerator: (id <SimpleRandomGenerator>) generator;
- setGenerator: (id <SplitRandomGenerator>) generator 
	setVirtualGenerator: (unsigned)vGen;
- reset;

// @protocol InternalState

USING

// @protocol ExponentialDist <DoubleDistribution, CREATABLE> 
- (double)getMean;
- (double)getSampleWithMean: (double)mean;

// @protocol DoubleDistribution <ProbabilityDistribution>
- (double)getDoubleSample;

// @protocol ProbabilityDistribution <SwarmObject, InternalState> 
- getGenerator;
- (unsigned)getVirtualGenerator;
- (BOOL)getOptionsInitialized;
- (unsigned long long int)getCurrentCount;

// @protocol InternalState
- (unsigned)getStateSize;		// size of buffer needed
- (void)putStateInto: (void *)buffer;	// save state data for later use
- (void)setStateFrom: (void *)buffer;	// set state from saved data
- (void)describe: outStream;	        // prints ascii data to stream
- (const char *)getName;		// returns name of object
- (unsigned)getMagic;			// object's 'magic number'

@end

