de.jstacs.algorithms.optimization
Class OneDimensionalFunction

java.lang.Object
  de.jstacs.algorithms.optimization.OneDimensionalFunction

All Implemented Interfaces:

Function

Direct Known Subclasses:

NegativeOneDimensionalFunction, OneDimensionalSubFunction, QuadraticFunction

public abstract class OneDimensionalFunction
extends Object
implements Function

This class implements the interface function for an one-dimensional function.

Author:

Jens Keilwagen

Constructor Summary

OneDimensionalFunction()

Method Summary

abstract double	evaluateFunction(double x) Evaluates the function at position x.
double	evaluateFunction(double[] x) Evaluates the function at a certain vector (in mathematical sense) x.
double[]	findMin(double lower, double fLower, double eps, double startDistance) This method returns a minimum x and the value f(x), starting the search at lower.
int	getDimensionOfScope() Returns the dimension of the scope of the function.

Methods inherited from class java.lang.Object

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

Constructor Detail

OneDimensionalFunction

public OneDimensionalFunction()

Method Detail

evaluateFunction

public double evaluateFunction(double[] x)
                        throws DimensionException,
                               EvaluationException

Description copied from interface: Function

Evaluates the function at a certain vector (in mathematical sense) x.

Specified by:

evaluateFunction in interface Function

Parameters:

x - the current vector

Returns:

the evaluation of the function

Throws:

DimensionException - if dim(x) != n, with f: R^n -> R

EvaluationException - if there was a mistake in evaluating the function

evaluateFunction

public abstract double evaluateFunction(double x)
                                 throws EvaluationException

Evaluates the function at position x.

Parameters:

x - the current position

Returns:

f(x)

Throws:

EvaluationException - if there was a mistake in evaluating the function

findMin

public double[] findMin(double lower,
                        double fLower,
                        double eps,
                        double startDistance)
                 throws EvaluationException

This method returns a minimum x and the value f(x), starting the search at lower. First the minimum is tried to be bracketed and then the interval is tried to be reduced. This method is a standard implementation and can be overwritten any time. It uses methods from the class Optimizer.

Parameters:

lower - the initial value of x

fLower - the value f(x)

eps - the threshold to stop the search of the minimum

startDistance - the initial distance for bracketing the minimum

Returns:

an array containing x at position 0 and f(x) at position 1

Throws:

EvaluationException - if there was a mistake in evaluating the function

See Also:

Optimizer

getDimensionOfScope

public final int getDimensionOfScope()

Description copied from interface: Function

Returns the dimension of the scope of the function.

Specified by:

getDimensionOfScope in interface Function

Returns:

dimension of the scope; n, with f: R^n -> R