--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/flys-artifacts/src/main/java/org/dive4elements/river/artifacts/math/fitting/Quad.java	Thu Apr 25 12:06:39 2013 +0200
@@ -0,0 +1,55 @@
+package org.dive4elements.river.artifacts.math.fitting;
+
+public class Quad
+extends      Function
+{
+    public static final Derivative DERIVATIVE =
+        new Derivative("W'(Q) = 2*n*Q+m") {
+
+        @Override
+        public org.dive4elements.river.artifacts.math.Function
+            instantiate(double [] parameters)
+        {
+            final double n2 = 2d*parameters[0];
+            final double m  = parameters[1];
+
+            return new org.dive4elements.river.artifacts.math.Function() {
+                @Override
+                public double value(double Q) {
+                    return n2*Q+m;
+                }
+            };
+        }
+    };
+
+    public static final Function INSTANCE = new Quad();
+
+    public Quad() {
+        super(
+            "quad",
+            "W(Q) = n*Q^2 + m*Q + b",
+            new String [] { "n", "m", "b" });
+    }
+
+    @Override
+    public double value(double x, double [] parameters) {
+        // n*Q^2 + m*Q + b <=> Q*(n*Q + m) + b
+        return x*(parameters[0]*x + parameters[1]) + parameters[2];
+    }
+
+    @Override
+    public double [] gradient(double x, double [] parameters) {
+        return new double [] { x*x, x, 1d };
+    }
+
+    @Override
+    public Derivative getDerivative() {
+        return DERIVATIVE;
+    }
+
+    @Override
+    public Function getInverse() {
+        return InvQuad.INSTANCE;
+    }
+}
+// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :