com.softsynth.jmsl.util
Class ExponentialInterpolator

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

All Implemented Interfaces:

Interpolator

public class ExponentialInterpolator
extends java.lang.Object
implements Interpolator

Interpolate a value along an exponentially rising curve defined by two points (x1,y1) and (x2,y2) where x1 < x2, y1 < y2.
The shape of f(x) = exp(x) on the interval [0..steepness] is fitted to the user's endpoints.
That is, (x1,y1) corresponds to (0, 1) and (x2,y2) corresponds to (1,e^steepness), and this new curve resembles a stretched or compressed version of the exp(x) function.

steepness values around 2 or 3 are reasonably gentle. Steepness around 8 and larger gets very steep, meaning most of your output range will be close to zero except for the very top end.

Constructor Summary

ExponentialInterpolator(double x1, double y1, double x2, double y2)
Construct an interpolator that fits a curve between (x1, y1) and (x2, y2) to an exponentially rising function.

Method Summary

double	interp(double x) Interpolate a value along exponential curve
static void	main(java.lang.String[] args) Use interpolator as a random distribution function
void	setInterp(double x1, double y1, double x2, double y2) Set two endpoints points on the desired curve, to be shaped as f(x)=exp(x) on (0,1)..(1,e) precondition: x1
void	setSteepness(double s) Reasonable values are 2..16

Methods inherited from class java.lang.Object

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

Constructor Detail

ExponentialInterpolator

public ExponentialInterpolator(double x1,
                               double y1,
                               double x2,
                               double y2)

Construct an interpolator that fits a curve between (x1, y1) and (x2, y2) to an exponentially rising function. Default steepness = 1. Higher values scales y2-y1 range and sharpens the curve's rise

Method Detail

setInterp

public void setInterp(double x1,
                      double y1,
                      double x2,
                      double y2)

Set two endpoints points on the desired curve, to be shaped as f(x)=exp(x) on (0,1)..(1,e)
precondition: x1

Specified by:

setInterp in interface Interpolator

interp

public double interp(double x)

Interpolate a value along exponential curve

Specified by:

interp in interface Interpolator

setSteepness

public void setSteepness(double s)

Reasonable values are 2..16

main

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

Use interpolator as a random distribution function