org.apache.commons.math4.fitting

Class AbstractCurveFitter

• Direct Known Subclasses:
GaussianCurveFitter, HarmonicCurveFitter, PolynomialCurveFitter, SimpleCurveFitter

public abstract class AbstractCurveFitter
extends Object
Base class that contains common code for fitting parametric univariate real functions y = f(pi;x), where x is the independent variable and the pi are the parameters.
A fitter will find the optimal values of the parameters by fitting the curve so it remains very close to a set of N observed points (xk, yk), 0 <= k < N.
An algorithm usually performs the fit by finding the parameter values that minimizes the objective function

∑yk - f(xk)2,

which is actually a least-squares problem. This class contains boilerplate code for calling the fit(Collection) method for obtaining the parameters. The problem setup, such as the choice of optimization algorithm for fitting a specific function is delegated to subclasses.
Since:
3.3
• Nested Class Summary

Nested Classes
Modifier and Type Class and Description
protected static class  AbstractCurveFitter.TheoreticalValuesFunction
Vector function for computing function theoretical values.
• Constructor Summary

Constructors
Constructor and Description
AbstractCurveFitter()
• Method Summary

All Methods
Modifier and Type Method and Description
double[] fit(Collection<WeightedObservedPoint> points)
Fits a curve.
protected LeastSquaresOptimizer getOptimizer()
Creates an optimizer set up to fit the appropriate curve.
protected abstract LeastSquaresProblem getProblem(Collection<WeightedObservedPoint> points)
Creates a least squares problem corresponding to the appropriate curve.
• Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
• Constructor Detail

• AbstractCurveFitter

public AbstractCurveFitter()
• Method Detail

• fit

public double[] fit(Collection<WeightedObservedPoint> points)
Fits a curve. This method computes the coefficients of the curve that best fit the sample of observed points.
Parameters:
points - Observations.
Returns:
the fitted parameters.
• getOptimizer

protected LeastSquaresOptimizer getOptimizer()
Creates an optimizer set up to fit the appropriate curve.

The default implementation uses a Levenberg-Marquardt optimizer.

Returns:
the optimizer to use for fitting the curve to the given points.
• getProblem

protected abstract LeastSquaresProblem getProblem(Collection<WeightedObservedPoint> points)
Creates a least squares problem corresponding to the appropriate curve.
Parameters:
points - Sample points.
Returns:
the least squares problem to use for fitting the curve to the given points.