org.apache.commons.math.util
Class ContinuedFraction

java.lang.Object
  org.apache.commons.math.util.ContinuedFraction

All Implemented Interfaces:

Serializable

public abstract class ContinuedFraction

extends Object

implements Serializable

Provides a generic means to evaluate continued fractions. Subclasses simply provided the a and b coefficients to evaluate the continued fraction.

References:

• Continued Fraction

Version:

$Revision: 1.14 $ $Date: 2004/06/23 16:26:16 $

See Also:

Serialized Form

Field Summary

(package private) static long

serialVersionUID Serialization UID

Constructor Summary

protected

ContinuedFraction() Default constructor.

Method Summary

double	evaluate(double x) Evaluates the continued fraction at the value x.
double	evaluate(double x, double epsilon) Evaluates the continued fraction at the value x.
double	evaluate(double x, double epsilon, int maxIterations) Evaluates the continued fraction at the value x.
double	evaluate(double x, int maxIterations) Evaluates the continued fraction at the value x.
protected abstract double	getA(int n, double x) Access the n-th a coefficient of the continued fraction.
protected abstract double	getB(int n, double x) Access the n-th b coefficient of the continued fraction.

Methods inherited from class java.lang.Object

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

Field Detail

serialVersionUID

static final long serialVersionUID

Serialization UID

See Also:

Constant Field Values

Constructor Detail

ContinuedFraction

protected ContinuedFraction()

Default constructor.

Method Detail

getA

protected abstract double getA(int n,
                               double x)

Access the n-th a coefficient of the continued fraction. Since a can be a function of the evaluation point, x, that is passed in as well.

Parameters:

n - the coefficient index to retrieve.

x - the evaluation point.

Returns:

the n-th a coefficient.

getB

protected abstract double getB(int n,
                               double x)

Access the n-th b coefficient of the continued fraction. Since b can be a function of the evaluation point, x, that is passed in as well.

Parameters:

n - the coefficient index to retrieve.

x - the evaluation point.

Returns:

the n-th b coefficient.

evaluate

public double evaluate(double x)
                throws MathException

Evaluates the continued fraction at the value x.

Parameters:

x - the evaluation point.

Returns:

the value of the continued fraction evaluated at x.

Throws:

MathException - if the algorithm fails to converge.

evaluate

public double evaluate(double x,
                       double epsilon)
                throws MathException

Evaluates the continued fraction at the value x.

Parameters:

x - the evaluation point.

epsilon - maximum error allowed.

Returns:

the value of the continued fraction evaluated at x.

Throws:

MathException - if the algorithm fails to converge.

evaluate

public double evaluate(double x,
                       int maxIterations)
                throws MathException

Evaluates the continued fraction at the value x.

Parameters:

x - the evaluation point.

maxIterations - maximum number of convergents

Returns:

the value of the continued fraction evaluated at x.

Throws:

MathException - if the algorithm fails to converge.

evaluate

public double evaluate(double x,
                       double epsilon,
                       int maxIterations)
                throws MathException

Evaluates the continued fraction at the value x. The implementation of this method is based on:

• O. E-gecio-glu, C . K. Koc, J. Rifa i Coma, On Fast Computation of Continued Fractions, Computers Math. Applic., 21(2--3), 1991, 167--169.

Parameters:

x - the evaluation point.

epsilon - maximum error allowed.

maxIterations - maximum number of convergents

Returns:

the value of the continued fraction evaluated at x.

Throws:

MathException - if the algorithm fails to converge.