## org.apache.commons.math.optimization.fitting
Class PolynomialFitter

    java.lang.Object
      org.apache.commons.math.optimization.fitting.PolynomialFitter

    public class PolynomialFitter

extends java.lang.Object

This class implements a curve fitting specialized for polynomials.

Polynomial fitting is a very simple case of curve fitting. The estimated coefficients are the polynomial coefficients. They are searched by a least square estimator.

Since:
  2.0
Version:
  $Revision: 811685 $ $Date: 2009-09-05 13:36:48 -0400 (Sat, 05 Sep 2009) $

Nested Class Summary
`private static class` `PolynomialFitter.ParametricPolynomial` Dedicated parametric polynomial class.

Field Summary
`private int` `degree` Polynomial degree.
`private CurveFitter` `fitter` Fitter for the coefficients.

Constructor Summary
`PolynomialFitter(int degree, DifferentiableMultivariateVectorialOptimizer optimizer)` Simple constructor.

Method Summary
`void` `addObservedPoint(double weight, double x, double y)` Add an observed weighted (x,y) point to the sample.
`PolynomialFunction` `fit()` Get the polynomial fitting the weighted (x, y) points.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### fitter

    private final CurveFitter fitter

  Fitter for the coefficients.

### degree

    private final int degree

  Polynomial degree.

Constructor Detail

### PolynomialFitter

    public PolynomialFitter(int degree,
                            DifferentiableMultivariateVectorialOptimizer optimizer)

  Simple constructor.

  The polynomial fitter built this way are complete polynomials, ie. a n-degree polynomial has n+1 coefficients.

  Parameters:
    `degree` - maximal degree of the polynomial
    `optimizer` - optimizer to use for the fitting

Method Detail

### addObservedPoint

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

  Add an observed weighted (x,y) point to the sample.

  Parameters:
    `weight` - weight of the observed point in the fit
    `x` - abscissa of the point
    `y` - observed value of the point at x, after fitting we should have P(x) as close as possible to this value

### fit

    public PolynomialFunction fit()
                           throws OptimizationException

  Get the polynomial fitting the weighted (x, y) points.

  Returns:
    polynomial function best fitting the observed points
  Throws:
    `OptimizationException` - if the algorithm failed to converge

Copyright (c) 2003-2011 Apache Software Foundation