Package jsl.utilities.rootfinding

Class RootFinder

java.lang.Object

jsl.utilities.math.DBHIterativeProcess

jsl.utilities.math.FunctionalIterator

jsl.utilities.rootfinding.RootFinder

Direct Known Subclasses:

BisectionRootFinder

public abstract class RootFinder
extends FunctionalIterator

Field Summary

Fields

Modifier and Type	Field	Description
protected double	fNeg	The value of the function at xNeg
protected double	fPos	The value of the function at xPos
protected double	myInitialPt	The initial point for the search
protected Interval	myInterval	The interval for the search
protected static int	numIterations	Used in the static methods for finding intervals
protected static double	searchFactor	used in the static methods for finding intervals
protected double	xNeg	Value at which the function's value is negative.
protected double	xPos	Value at which the function's value is positive.

Fields inherited from class jsl.utilities.math.FunctionalIterator

f, result

Constructor Summary

Constructors

Constructor	Description
RootFinder()
RootFinder(FunctionIfc func, double xLower, double xUpper)
RootFinder(FunctionIfc func, Interval interval)

Method Summary

Modifier and Type	Method	Description
boolean	contains(double x)	Checks to see if the the supplied point is within the search interval
static boolean	findInterval(FunctionIfc func, Interval interval)	Using the supplied function and the initial interval provided, try to find a bracketing interval by expanding the interval outward
static java.util.List<Interval>	findInterval(FunctionIfc func, Interval interval, int n, int nmax)	Given a function and a starting interval, subdivide the interval into n subintervals and attempt to find nmax bracketing intervals that contain roots
double	getLowerLimit()	The lower limit for the search interval
double	getUpperLimit()	The upper limit for the search interval
boolean	hasRoot(double xLower, double xUpper)	Returns true if the supplied interval contains a root
boolean	hasRoot(Interval interval)	Returns true if the supplied interval contains a root
static boolean	hasRoot(FunctionIfc func, double xLower, double xUpper)	Returns true if the supplied interval contains a root
void	setInitialPoint(double initialPt)	Sets the initial starting point for the search.
void	setInterval(double xLower, double xUpper)	Sets the bracketing interval within which the root should be found.
void	setInterval(Interval interval)	Sets the search interval for the search
void	setInterval(FunctionIfc func, double xLower, double xUpper)	Sets the bracketing interval within which the root should be found.
void	setInterval(FunctionIfc func, Interval interval)	Sets the bracketing interval within which the root should be found.
java.lang.String	toString()	Returns a String representation of the finder

Methods inherited from class jsl.utilities.math.FunctionalIterator

getResult, relativePrecision, setFunction

Methods inherited from class jsl.utilities.math.DBHIterativeProcess

evaluate, evaluateIteration, finalizeIterations, getDesiredPrecision, getIterations, getMaximumIterations, getPrecision, hasConverged, initializeIterations, relativePrecision, setDesiredPrecision, setMaximumIterations

Methods inherited from class java.lang.Object

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

Field Detail

xNeg

protected double xNeg

Value at which the function's value is negative.

xPos

protected double xPos

Value at which the function's value is positive.

fNeg

protected double fNeg

The value of the function at xNeg

fPos

protected double fPos

The value of the function at xPos

myInterval

protected Interval myInterval

The interval for the search

myInitialPt

protected double myInitialPt

The initial point for the search

numIterations

protected static int numIterations

Used in the static methods for finding intervals

searchFactor

protected static double searchFactor

used in the static methods for finding intervals

Constructor Detail

RootFinder

public RootFinder()

RootFinder

public RootFinder(FunctionIfc func,
                  Interval interval)

RootFinder

public RootFinder(FunctionIfc func,
                  double xLower,
                  double xUpper)

Method Detail

toString

public java.lang.String toString()

Returns a String representation of the finder

Overrides:

toString in class java.lang.Object

Returns:

A String with basic results

hasRoot

public final boolean hasRoot(Interval interval)

Returns true if the supplied interval contains a root

Parameters:

interval -

Returns:

hasRoot

public boolean hasRoot(double xLower,
                       double xUpper)

Returns true if the supplied interval contains a root

Parameters:

xLower -

xUpper -

Returns:

hasRoot

public static boolean hasRoot(FunctionIfc func,
                              double xLower,
                              double xUpper)

Returns true if the supplied interval contains a root

Parameters:

func -

xLower -

xUpper -

Returns:

findInterval

public static boolean findInterval(FunctionIfc func,
                                   Interval interval)

Using the supplied function and the initial interval provided, try to find a bracketing interval by expanding the interval outward

Parameters:

func -

interval -

Returns:

findInterval

public static java.util.List<Interval> findInterval(FunctionIfc func,
                                                    Interval interval,
                                                    int n,
                                                    int nmax)

Given a function and a starting interval, subdivide the interval into n subintervals and attempt to find nmax bracketing intervals that contain roots

Parameters:

func -

interval -

n -

nmax -

Returns:

The list of bracketing intervals

setInterval

public final void setInterval(Interval interval)

Sets the search interval for the search

Parameters:

interval -

setInterval

public void setInterval(double xLower,
                        double xUpper)

Sets the bracketing interval within which the root should be found. Throws IllegalArgumentExceptons if the lower limit is > upper limit and if the function does not cross the axis within the provided interval.

Parameters:

xLower -

xUpper -

setInitialPoint

public void setInitialPoint(double initialPt)

Sets the initial starting point for the search. The starting point must be in the interval defined for the search or an IllegalArgumentException will be thrown.

Parameters:

initialPt -

contains

public final boolean contains(double x)

Checks to see if the the supplied point is within the search interval

Parameters:

x -

Returns:

getLowerLimit

public final double getLowerLimit()

The lower limit for the search interval

Returns:

getUpperLimit

public final double getUpperLimit()

The upper limit for the search interval

Returns:

setInterval

public final void setInterval(FunctionIfc func,
                              Interval interval)

Sets the bracketing interval within which the root should be found. Throws IllegalArgumentExceptons if the lower limit is > upper limit and if the function does not cross the axis within the provided interval.

Parameters:

func -

interval -

setInterval

public final void setInterval(FunctionIfc func,
                              double xLower,
                              double xUpper)

Sets the bracketing interval within which the root should be found. Throws IllegalArgumentExceptons if the lower limit is > upper limit and if the function does not cross the axis within the provided interval.

Parameters:

func - Sets the function to be evaluated, must not be null

xLower -

xUpper -