--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/artifacts/src/main/java/org/dive4elements/river/artifacts/model/extreme/Curve.java	Thu Apr 25 15:23:37 2013 +0200
@@ -0,0 +1,144 @@
+package org.dive4elements.river.artifacts.model.extreme;
+
+import org.dive4elements.river.artifacts.math.Function;
+import org.dive4elements.river.artifacts.math.NaNFunction;
+import org.dive4elements.river.artifacts.math.UnivariateRealFunctionFunction;
+
+import org.dive4elements.river.artifacts.math.fitting.FunctionFactory;
+
+import java.io.Serializable;
+
+import java.lang.ref.SoftReference;
+
+import org.apache.commons.math.analysis.interpolation.SplineInterpolator;
+
+import org.apache.commons.math.exception.MathIllegalArgumentException;
+
+import org.apache.log4j.Logger;
+
+/** An extrapolating W/Q function/curve. */
+public class Curve
+implements   Serializable, Function
+{
+    private static Logger log = Logger.getLogger(Curve.class);
+
+    protected double [] qs;
+    protected double [] ws;
+    protected String    function;
+    protected double [] coeffs;
+    protected double    chiSqr;
+
+    /** Suggested maximum value for q to input. */
+    protected double    suggestedMaxQ;
+
+    // The spline is pretty heavy weight so cache it with a soft ref only.
+    protected transient SoftReference<Function> spline;
+    protected transient Function                extrapolation;
+
+    public Curve() {
+    }
+
+    public Curve(
+        double [] qs,
+        double [] ws,
+        String    function,
+        double [] coeffs,
+        double    chiSqr
+    ) {
+        this.qs       = qs;
+        this.ws       = ws;
+        this.function = function;
+        this.coeffs   = coeffs;
+        this.suggestedMaxQ = Double.MAX_VALUE;
+    }
+
+    public double [] getQs() {
+        return qs;
+    }
+
+    public double [] getWs() {
+        return ws;
+    }
+
+    public String getFunction() {
+        return function;
+    }
+
+    public double [] getCoeffs() {
+        return coeffs;
+    }
+
+
+    public void setSuggestedMaxQ(double newMaxQ) {
+        this.suggestedMaxQ = newMaxQ;
+    }
+
+
+    public double getSuggestedMaxQ() {
+        return this.suggestedMaxQ;
+    }
+
+
+    /** Calculate value at given x. */
+    @Override
+    public double value(double x) {
+        if (qs == null || x < qs[0]) return Double.NaN;
+        return (x <= qs[qs.length-1]
+            ? getSpline()
+            : getExtrapolation()).value(x);
+    }
+
+    protected synchronized Function getExtrapolation() {
+        if (extrapolation == null) {
+            org.dive4elements.river.artifacts.math.fitting.Function
+                f = FunctionFactory.getInstance().getFunction(function);
+
+            extrapolation = f != null
+                ? f.instantiate(coeffs)
+                : NaNFunction.INSTANCE;
+        }
+        return extrapolation;
+    }
+
+    /**
+     * Gets the chiSqr for this instance.
+     *
+     * @return The chiSqr.
+     */
+    public double getChiSqr() {
+        return this.chiSqr;
+    }
+
+    /**
+     * Sets the chiSqr for this instance.
+     *
+     * @param chiSqr The chiSqr.
+     */
+    public void setChiSqr(double chiSqr) {
+        this.chiSqr = chiSqr;
+    }
+
+    protected synchronized Function getSpline() {
+        Function sp;
+        if (spline != null) {
+            if ((sp = spline.get()) != null) {
+                return sp;
+            }
+        }
+        spline = new SoftReference<Function>(sp = createSpline());
+        return sp;
+    }
+
+    protected Function createSpline() {
+        SplineInterpolator interpolator = new SplineInterpolator();
+        try {
+            return new UnivariateRealFunctionFunction(
+                interpolator.interpolate(qs, ws));
+        }
+        catch (MathIllegalArgumentException miae) {
+            log.debug("creation on spline failed", miae);
+            return NaNFunction.INSTANCE;
+        }
+    }
+}
+// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf-8 :