com.softsynth.jmsl.util
Class EventDistributions

java.lang.Object
  com.softsynth.jmsl.util.EventDistributions

public class EventDistributions
extends java.lang.Object

Implements 'entry delay approach' to generate event densities. From Charles Ames's suggestions in letter dated March 17, 1992 Source for Myhill distribution and additional comments from "A Catalog of Statistical Distributions" by Charles Ames. Leonardo Music Journal, Vol. 1 No. 1, 1991 This code implements the exponential distribution and the Myhill distribution. The Myhill distribution can be thought of as a more flexible exponential distribution; one whose variance can be controlled. This control is reflected in a ratio whose value causes the Myhill distribution to more or less approximate the exponential distribution. When the ratio is high (above 128), the two distributions are indistinguishable. When ratio is low, the Myhill transform generates increasingly regular, periodic patterns, as opposed to the clustering and leaps of the exponential transform.

Author:

Nick Didkovsky and Phil Burk, copyright 1997 Nick Didkovsky and Phil Burk, all rights reserved.
JMSL is based on Hierarchical Music Specification Language (HMSL), which was created by Phil Burk, Larry Polansky, and David Rosenboom at the Mills College Center for Contemporary Music.

Constructor Summary

EventDistributions()

Method Summary

static double	genEntryDelayLog(double meanEventDensity) GENERATE ENTRY DELAYS FROM LOGARITHMIC DISTRIBUTION This gives you lots of short entry delays with an occasional long one.
static double	genEntryDelayMyhill(double meanEventDensity, double ratio) GENERATE ENTRY DELAYS FROM MYHILL DISTRIBUTION This distribution maintains the balance of long to short durations that makes the logarithmic distribution appealing, additionally giving you control over mean AND variance.
static void	main(java.lang.String[] args) Print out distributed entry delays

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

EventDistributions

public EventDistributions()

Method Detail

genEntryDelayLog

public static double genEntryDelayLog(double meanEventDensity)

GENERATE ENTRY DELAYS FROM LOGARITHMIC DISTRIBUTION
This gives you lots of short entry delays with an occasional long one. A nice balance, but with no control over standard deviation from the mean event density. These comments taken from Ames, LMJ.

         f(u,m,sigma) = -(ln(1-u)) / m
         where m = (mean event density) and u is a driver value
         and distribution of entry delays is exponential
        

genEntryDelayMyhill

public static double genEntryDelayMyhill(double meanEventDensity,
                                         double ratio)

GENERATE ENTRY DELAYS FROM MYHILL DISTRIBUTION
This distribution maintains the balance of long to short durations that makes the logarithmic distribution appealing, additionally giving you control over mean AND variance. Also eliminates exceedingly short and exceedingly long values. These comments were taken from Ames, LMJ.

         f = -ln[(U1-U2)u + U2] / m
         where U2 = the (1-R)th root of R and U1 = U2^R
         R is a ratio relating the maximum and minimum samples.
         m is mean event density
         u is a driver value

         Comments taken from Ames on Ratio values:
         Ratio represents approximation to pure exponential.
         It is the ratio relating the maximum and minimum allowed samples.
         Thus a ratio of 5.0 with a mean of 7.0 would yield a range
         from 2.8 to 14.0, since 14/2.8=5 and is centered on 7
         Ratios over 128 makes Myhill behave indistinguishably from exponential.
         Ratios from 4 to 16 produce approximation ranging from 50% to 75%
         Ratios less than 2 are 'drunkenly regular'.
         Closer and closer to unity ratios generate more and more regular event patterns.
         

main

public static void main(java.lang.String[] args)

Print out distributed entry delays