/**
* Fit an harmonic function to the observed points.
*
* @return harmonic function best fitting the observed points
* @throws OptimizationException if the sample is too short or if the first guess cannot be
* computed
*/
public HarmonicFunction fit() throws OptimizationException {
// shall we compute the first guess of the parameters ourselves ?
if (parameters == null) {
final WeightedObservedPoint[] observations = fitter.getObservations();
if (observations.length < 4) {
throw new OptimizationException(
LocalizedFormats.INSUFFICIENT_OBSERVED_POINTS_IN_SAMPLE, observations.length, 4);
}
HarmonicCoefficientsGuesser guesser = new HarmonicCoefficientsGuesser(observations);
guesser.guess();
parameters =
new double[] {
guesser.getGuessedAmplitude(), guesser.getGuessedPulsation(), guesser.getGuessedPhase()
};
}
try {
double[] fitted = fitter.fit(new ParametricHarmonicFunction(), parameters);
return new HarmonicFunction(fitted[0], fitted[1], fitted[2]);
} catch (FunctionEvaluationException fee) {
// should never happen
throw new RuntimeException(fee);
}
}
/**
* Add an observed weighted (x,y) point to the sample.
*
* @param weight weight of the observed point in the fit
* @param x abscissa of the point
* @param y observed value of the point at x, after fitting we should have P(x) as close as
* possible to this value
*/
public void addObservedPoint(double weight, double x, double y) {
fitter.addObservedPoint(weight, x, y);
}