Package xal.extension.fit

Class LinearFit

java.lang.Object

xal.extension.fit.LinearFit

public class LinearFit
extends Object

Fit a set of x,y data pairs to a line where y = slope * x + intercept.

Field Summary

Fields

Modifier and Type	Field	Description
protected double	correlationCoefficient
protected double	intercept
protected boolean	needsUpdate
protected double	slope
protected final MutableUnivariateStatistics	xStats
protected final MutableUnivariateStatistics	xxStats
protected final MutableUnivariateStatistics	xyStats
protected final MutableUnivariateStatistics	yStats
protected final MutableUnivariateStatistics	yyStats

Constructor Summary

Constructors

Constructor	Description
LinearFit()	Constructor

Method Summary

Modifier and Type	Method	Description
void	addSample(double x, double y)	Add a new x,y pair.
double	estimateY(double x)	Estimate the dependent variable (y) given the independent variable (x).
double	getCorrelationCoefficient()	Get the correlation coefficient.
double	getIntercept()	Get the intercept performing a fit if needed.
double	getMeanSquareOrdinateError()	Get the mean square error of the y value with respect to the fitted line.
double	getSlope()	Get the slope performing a fit if needed.
protected void	performFit()	Calculate the slope and intercept.
protected void	performFitIfNeeded()	Perform a linear fit if the the fit needs to be updated due to newly added data.
String	toString()	Generate a string representation of the linear equation.

Methods inherited from class java.lang.Object

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

Field Details

xStats

protected final MutableUnivariateStatistics xStats

yStats

protected final MutableUnivariateStatistics yStats

xxStats

protected final MutableUnivariateStatistics xxStats

xyStats

protected final MutableUnivariateStatistics xyStats

yyStats

protected final MutableUnivariateStatistics yyStats

needsUpdate

protected boolean needsUpdate

slope

protected double slope

intercept

protected double intercept

correlationCoefficient

protected double correlationCoefficient

Constructor Details

LinearFit

public LinearFit()

Constructor

Method Details

addSample

public void addSample(double x,
 double y)

Add a new x,y pair.

getSlope

public double getSlope()

Get the slope performing a fit if needed.

Returns:

the fitted slope

getIntercept

public double getIntercept()

Get the intercept performing a fit if needed.

Returns:

the fitted intercept

getCorrelationCoefficient

public double getCorrelationCoefficient()

Get the correlation coefficient.

Returns:

the correlation coefficient.

estimateY

public double estimateY(double x)

Estimate the dependent variable (y) given the independent variable (x).

Parameters:

x - the independent variable

Returns:

the dependent variable

getMeanSquareOrdinateError

public double getMeanSquareOrdinateError()

Get the mean square error of the y value with respect to the fitted line. The square root of this number gives an indication of the uncertainty in y value estimates under certain assumptions about the error distribution.

Returns:

the mean square error of the y value with respect to the fitted line

performFitIfNeeded

protected void performFitIfNeeded()

Perform a linear fit if the the fit needs to be updated due to newly added data.

performFit

protected void performFit()

Calculate the slope and intercept.

toString

public String toString()

Generate a string representation of the linear equation.

Overrides:

toString in class Object

Returns:

a string representation of the linear equation