--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gnv-artifacts/src/main/java/de/intevation/gnv/math/LinearFunction.java	Fri Sep 28 12:13:53 2012 +0200
@@ -0,0 +1,57 @@
+package de.intevation.gnv.math;
+
+import org.apache.commons.math.optimization.fitting.ParametricRealFunction;
+
+import org.apache.commons.math.FunctionEvaluationException;
+
+import org.apache.commons.math.analysis.UnivariateRealFunction;
+
+/**
+ *  @author Sascha L. Teichmann (sascha.teichmann@intevation.de)
+ */
+public class LinearFunction
+implements   ParametricRealFunction
+{
+    public static final LinearFunction INSTANCE = new LinearFunction();
+
+    public static class Univariate 
+    implements          UnivariateRealFunction
+    {
+        protected double m;
+        protected double b;
+
+        public Univariate() {
+        }
+
+        public Univariate(double x1, double y1, double x2, double y2) {
+            if (y1 == y2) {
+                m = 0d;
+                b = (x1 + x2)*0.5d;
+            }
+            else {
+                m = (x1 - x2)/(y1 - y2);
+                b = y1 - m*x1;
+            }
+        }
+
+        public double value(double x) {
+            return m*x + b;
+        }
+    } // class Univariate
+
+    public LinearFunction() {
+    }
+
+    public double value(double x, double [] parameters)
+    throws FunctionEvaluationException 
+    {
+        return x*parameters[0] + parameters[1];
+    }
+
+    public double [] gradient(double x, double [] parameters) 
+    throws FunctionEvaluationException 
+    {
+        return new double [] { x, 1f };
+    }
+}
+// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :