Re: poisson distr ?

[gepr]

There is one.  Just include random.h.  Here's the protocol:


@protocol PoissonDist <UnsignedDistribution, CREATABLE>
//S: Poisson distribution
//D: A distribution used to model the integer number of occurrences 
//D: of some event over an interval of time or space. 

CREATING
//M: Use this create message if the generator to be attached is a Simple one
//M: and both the occurrence rate and the interval are set at create time:
+ create     : (id <Zone>)aZone
 setGenerator: (id <SimpleRandomGenerator>)generator
 setOccurRate: (double) anOccurRate
  setInterval: (double) anInterval;

//M: Use this create message if the generator to be attached is a Split one and
//M: both the occurrence rate and the interval are to be set at create time:
+ create             : (id <Zone>)aZone
         setGenerator: (id <SplitRandomGenerator>)generator
  setVirtualGenerator: (unsigned)vGen
         setOccurRate: (double) anOccurRate
          setInterval: (double) anInterval;

SETTING

//M: The setInterval method only sets the interval parameter; the occurRate 
//M: parameter is left unchanged from its previous or initialized value 
- setInterval: (double) anInterval;

//M: The setOccurRate method only sets the occurRate parameter; the interval 
//M: parameter is left unchanged from its previous or initialized value 
- setOccurRate: (double) anOccurRate;

//M: The setOccurRate:setInterval method sets both the occurrence rate 
//M: and the interval parameters.
- setOccurRate: (double) anOccurRate
   setInterval: (double) anInterval;

USING

//M: The getOccurRate method returns the occurrence rate parameter.
- (double) getOccurRate;

//M: The getInterval method returns the interval parameter.
- (double) getInterval;

//M: The getUnsignedSampleWithInterval method returns a sample value using 
//M: the distribution's current occurrence rate and new interval value. 
//M: Causes an error if the occurrence rate has not been previously set.
- (unsigned) getUnsignedSampleWithInterval: (double) anInterval;

//M: The getUnsignedSampleWithOccurRate:andInterval method returns 
//M: a sample value for the specified occurrence rate and interval. 
//M: Does not change the the distribution's parameter values set by 
//M: the setter methods.
- (unsigned) getUnsignedSampleWithOccurRate: (double) anOccurRate
                         withInterval: (double) anInterval;

@end

Rick Riolo writes:
 > has anyone implemented a poisson distribution generator
 > in (objective c) swarm?  (i didn't see it in the docs,
 > but maybe i missed it?)
 > if you have one, or have one in C i suppose, 
 > could you please post/point us to the source?

-- 
glen e. p. ropella              =><=                           Hail Eris!
H: 831.335.4950                              http://www.ropella.net/~gepr
M: 831.247.7901                               http://www.tempusdictum.com


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