de.jstacs.algorithms.optimization
Class QuadraticFunction

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

All Implemented Interfaces:

Function

public class QuadraticFunction
extends OneDimensionalFunction

This class implements a quadratic function.

Author:

Jens Keilwagen

Constructor Summary

QuadraticFunction(double a, double b, double c)
This constructor creates a quadratic function with: a*x2 + b*x + c.

QuadraticFunction(double x1, double fx1, double x2, double fx2, double x3, double fx3)
This constructor creates an instance from 3 points (x,f(x)).

Method Summary

double	evaluateFunction(double x) Evaluates the function at position x.
double	findMax() This method returns the maximum of the QuadraticFunction.
double	findMin() This method returns the minimum of the QuadraticFunction.
double	getExtremum() This method returns the extremum of the QuadraticFunction.
String	toString()

Methods inherited from class de.jstacs.algorithms.optimization.OneDimensionalFunction

evaluateFunction, findMin, getDimensionOfScope

Methods inherited from class java.lang.Object

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

Constructor Detail

QuadraticFunction

public QuadraticFunction(double a,
                         double b,
                         double c)

This constructor creates a quadratic function with: a*x2 + b*x + c.

Parameters:

a - the coefficient for x2

b - the coefficient for x

c - the constant

QuadraticFunction

public QuadraticFunction(double x1,
                         double fx1,
                         double x2,
                         double fx2,
                         double x3,
                         double fx3)
                  throws IOException

This constructor creates an instance from 3 points (x,f(x)).

Parameters:

x1 - the first x-coordinate

fx1 - f(x1)

x2 - the second x-coordinate

fx2 - f(x2)

x3 - the third x-coordinate

fx3 - f(x3)

Throws:

IOException - if the quadratic function could not be determined

Method Detail

evaluateFunction

public double evaluateFunction(double x)

Description copied from class: OneDimensionalFunction

Evaluates the function at position x.

Specified by:

evaluateFunction in class OneDimensionalFunction

Parameters:

x - the current position

Returns:

f(x)

findMax

public double findMax()
               throws IOException

This method returns the maximum of the QuadraticFunction.

Returns:

the maximum

Throws:

IOException - if no maximum exists

findMin

public double findMin()
               throws IOException

This method returns the minimum of the QuadraticFunction.

Returns:

the minimum

Throws:

IOException - if no minimum exists

getExtremum

public double getExtremum()
                   throws IOException

This method returns the extremum of the QuadraticFunction.

Returns:

the extremum

Throws:

IOException - if no extremum exists

toString

public String toString()

Overrides:

toString in class Object