sascha@3733: package de.intevation.flys.artifacts.model.extreme;
sascha@3733: 
sascha@3733: import de.intevation.flys.artifacts.math.Function;
sascha@3733: import de.intevation.flys.artifacts.math.NaNFunction;
sascha@3733: import de.intevation.flys.artifacts.math.UnivariateRealFunctionFunction;
sascha@3733: 
sascha@3733: import de.intevation.flys.artifacts.math.fitting.FunctionFactory;
sascha@3733: 
sascha@3733: import de.intevation.flys.artifacts.model.QW;
sascha@3733: 
sascha@3733: import java.io.Serializable;
sascha@3733: 
sascha@3733: import java.lang.ref.SoftReference;
sascha@3733: 
sascha@3733: import org.apache.commons.math.analysis.interpolation.SplineInterpolator;
sascha@3733: 
sascha@3733: import org.apache.commons.math.exception.MathIllegalArgumentException;
sascha@3733: 
sascha@3733: import org.apache.log4j.Logger;
sascha@3733: 
sascha@3733: public class Curve
sascha@3733: implements   Serializable, Function
sascha@3733: {
sascha@3733:     private static Logger log = Logger.getLogger(Curve.class);
sascha@3733: 
sascha@3733:     protected QW []     qws;
sascha@3733:     protected String    function;
sascha@3733:     protected double [] coeffs;
sascha@3733: 
sascha@3733:     // The spline is pretty heavy weight so cache it with a soft ref only.
sascha@3733:     protected transient SoftReference<Function> spline;
sascha@3733:     protected transient Function                extrapolation;
sascha@3733: 
sascha@3733:     public Curve() {
sascha@3733:     }
sascha@3733: 
sascha@3733:     public Curve(QW [] qws, String function, double [] coeffs) {
sascha@3733:         this.qws      = qws;
sascha@3733:         this.function = function;
sascha@3733:         this.coeffs   = coeffs;
sascha@3733:     }
sascha@3733: 
sascha@3733:     public QW [] getQWs() {
sascha@3733:         return qws;
sascha@3733:     }
sascha@3733: 
sascha@3733:     public String getFunction() {
sascha@3733:         return function;
sascha@3733:     }
sascha@3733: 
sascha@3733:     public double [] getCoeffs() {
sascha@3733:         return coeffs;
sascha@3733:     }
sascha@3733: 
sascha@3733:     @Override
sascha@3733:     public double value(double x) {
sascha@3733:         if (x < qws[0].getQ()) return Double.NaN;
sascha@3733:         return (x <= qws[qws.length-1].getQ()
sascha@3733:             ? getSpline()
sascha@3733:             : getExtrapolation()).value(x);
sascha@3733:     }
sascha@3733: 
sascha@3733:     protected synchronized Function getExtrapolation() {
sascha@3733:         if (extrapolation == null) {
sascha@3733:             de.intevation.flys.artifacts.math.fitting.Function
sascha@3733:                 f = FunctionFactory.getInstance().getFunction(function);
sascha@3733: 
sascha@3733:             extrapolation = f != null
sascha@3733:                 ? f.instantiate(coeffs)
sascha@3733:                 : NaNFunction.INSTANCE;
sascha@3733:         }
sascha@3733:         return extrapolation;
sascha@3733:     }
sascha@3733: 
sascha@3733:     protected synchronized Function getSpline() {
sascha@3733:         Function sp;
sascha@3733:         if (spline != null) {
sascha@3733:             if ((sp = spline.get()) != null) {
sascha@3733:                 return sp;
sascha@3733:             }
sascha@3733:         }
sascha@3733:         spline = new SoftReference(sp = createSpline());
sascha@3733:         return sp;
sascha@3733:     }
sascha@3733: 
sascha@3733:     protected Function createSpline() {
sascha@3733:         SplineInterpolator interpolator = new SplineInterpolator();
sascha@3733:         double [] qs = new double[qws.length];
sascha@3733:         double [] ws = new double[qws.length];
sascha@3733:         for (int i = 0; i < qws.length; ++i) {
sascha@3733:             QW qw = qws[i];
sascha@3733:             qs[i] = qw.getQ();
sascha@3733:             ws[i] = qw.getW();
sascha@3733:         }
sascha@3733:         try {
sascha@3733:             return new UnivariateRealFunctionFunction(
sascha@3733:                 interpolator.interpolate(qs, ws));
sascha@3733:         }
sascha@3733:         catch (MathIllegalArgumentException miae) {
sascha@3733:             log.debug("creation on spline failed", miae);
sascha@3733:             return NaNFunction.INSTANCE;
sascha@3733:         }
sascha@3733:     }
sascha@3733: }
sascha@3733: // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf-8 :