org.spaceroots.mantissa.fitting

Class AbstractCurveFitter

java.lang.Object

org.spaceroots.mantissa.fitting.AbstractCurveFitter

All Implemented Interfaces:

java.io.Serializable, EstimationProblem

Direct Known Subclasses:

HarmonicFitter, PolynomialFitter

public abstract class AbstractCurveFitter
extends java.lang.Object
implements EstimationProblem, java.io.Serializable

This class is the base class for all curve fitting classes in the package.

This class handles all common features of curve fitting like the sample points handling. It declares two methods (valueAt(double) and partial(double, org.spaceroots.mantissa.estimation.EstimatedParameter)) which should be implemented by sub-classes to define the precise shape of the curve they represent.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	AbstractCurveFitter.FitMeasurement This class represents the fit measurements.

Method Summary

Modifier and Type	Method and Description
void	addWeightedPair(double weight, double x, double y) Add a weighted (x,y) pair to the sample.
double[]	fit() Perform the fitting.
EstimatedParameter[]	getAllParameters() Get all the parameters of the problem.
WeightedMeasurement[]	getMeasurements() Get the measurements of an estimation problem.
EstimatedParameter[]	getUnboundParameters() Get the unbound parameters of the problem.
abstract double	partial(double x, EstimatedParameter p) Get the derivative of the function at x with respect to parameter p.
abstract double	valueAt(double x) Get the value of the function at x according to the current parameters value.

Methods inherited from class java.lang.Object

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

Method Detail

addWeightedPair

public void addWeightedPair(double weight,
                            double x,
                            double y)

Add a weighted (x,y) pair to the sample.

Parameters:

weight - weight of this pair in the fit

x - abscissa

y - ordinate, we have y = f (x)

fit

public double[] fit()
             throws EstimationException

Perform the fitting.

This method compute the coefficients of the curve that best fit the sample of weighted pairs previously given through calls to the addWeightedPair method.

Returns:

coefficients of the curve

Throws:

EstimationException - if the fitting is not possible (for example if the sample has to few independant points)

getMeasurements

public WeightedMeasurement[] getMeasurements()

Description copied from interface: EstimationProblem

Get the measurements of an estimation problem.

Specified by:

getMeasurements in interface EstimationProblem

Returns:

measurements

getUnboundParameters

public EstimatedParameter[] getUnboundParameters()

Get the unbound parameters of the problem. For a curve fitting, none of the function coefficient is bound.

Specified by:

getUnboundParameters in interface EstimationProblem

Returns:

unbound parameters

getAllParameters

public EstimatedParameter[] getAllParameters()

Get all the parameters of the problem.

Specified by:

getAllParameters in interface EstimationProblem

Returns:

parameters

valueAt

public abstract double valueAt(double x)

Get the value of the function at x according to the current parameters value.

Parameters:

x - abscissa at which the theoretical value is requested

Returns:

theoretical value at x

partial

public abstract double partial(double x,
                               EstimatedParameter p)

Get the derivative of the function at x with respect to parameter p.

Parameters:

x - abscissa at which the partial derivative is requested

p - parameter with respect to which the derivative is requested

Returns:

partial derivative