edu.brook.ascape.util
Class Function

java.lang.Object
  |
  +--edu.brook.ascape.util.Function

public abstract class Function

extends java.lang.Object

implements java.io.Serializable, java.lang.Cloneable

A one-dimensional function.

Since:

1.0

Version:

1.0

See Also:

Serialized Form

Field Summary

protected static double	f2 The result value for the second measurement.
protected static double	f3 The result value for the third measurement.
protected double	gap1 The X axis gap between the first and second measurements
protected double	gap2 The X axis gap between the second and third measurements (after one measurement has been dropped, leaving three total.)
static double	resolution Desired resolution of maximization.
static double	sectLarge Large end of golden section.
static double	sectSmall Small end of golden section.
static double	tau Tau "magic" number.
protected static double	x1 The first measurement of the current interval.
protected static double	x2 The second measurement of the current interval.
protected static double	x3 The third measurement of the current interval.
protected static double	x4 The fourth measurement of the current interval.

Constructor Summary

Function()

Method Summary

java.lang.Object	clone() Clones this function.
double	maximize() Maximize the output of this function, assuming function is unimodal, using a golden section search strategy.
double	solveFor(double x) Solve this (single-variable) function.

Methods inherited from class java.lang.Object

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

Field Detail

tau

public static final double tau

Tau "magic" number. ~1.61803

sectLarge

public static final double sectLarge

Large end of golden section. ~.61803

sectSmall

public static final double sectSmall

Small end of golden section. ~.38197

resolution

public static final double resolution

Desired resolution of maximization.

x1

protected static double x1

The first measurement of the current interval. For minor performance reasons, this and other measurements are not initialized in the body of the maximization functions. This can easily be changed if desired. Also, please note that this class is _not_ thread safe; in order to make it so, simply initialize the following variables within a contructor (or in the method body), make them non-static, and synchronize the methods as appropriate.

x2

protected static double x2

The second measurement of the current interval.

x3

protected static double x3

The third measurement of the current interval.

x4

protected static double x4

The fourth measurement of the current interval.

f2

protected static double f2

The result value for the second measurement.

f3

protected static double f3

The result value for the third measurement.

gap1

protected double gap1

The X axis gap between the first and second measurements

gap2

protected double gap2

The X axis gap between the second and third measurements (after one measurement has been dropped, leaving three total.)

Constructor Detail

Function

public Function()

Method Detail

maximize

public double maximize()

Maximize the output of this function, assuming function is unimodal, using a golden section search strategy. See Press, Flannery, Teukolsky, Vetterling _Numerical Recipes in *_ 10.1 for general guidelines, but not for specific implementation.

Returns:

the optimal input variable

solveFor

public double solveFor(double x)

Solve this (single-variable) function. Override to define your own function.

Parameters:

x - the variable input parameter

Returns:

the output value

clone

public java.lang.Object clone()

Clones this function.

Overrides:

clone in class java.lang.Object