--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/flys-artifacts/src/main/java/org/dive4elements/river/artifacts/math/fitting/App.java	Thu Apr 25 12:06:39 2013 +0200
@@ -0,0 +1,127 @@
+package org.dive4elements.river.artifacts.math.fitting;
+
+import java.util.List;
+import java.util.Map;
+import java.util.ArrayList;
+import java.util.TreeMap;
+import java.util.Comparator;
+
+import java.io.IOException;
+import java.io.BufferedReader;
+import java.io.Reader;
+import java.io.InputStreamReader;
+
+import org.apache.commons.math.optimization.fitting.CurveFitter;
+
+import org.apache.commons.math.optimization.general.LevenbergMarquardtOptimizer;
+
+import org.apache.commons.math.MathException;
+
+public class App
+{
+    public static final double EPS = 1e-5;
+
+    public static final String FUNCTION_NAME =
+        System.getProperty("function", "linear");
+
+    public static final Comparator<Double> EPS_CMP =
+        new Comparator<Double>()  {
+            @Override
+            public int compare(Double a, Double b) {
+                double diff = a - b;
+                if (diff < -EPS) return -1;
+                if (diff >  EPS) return +1;
+                return 0;
+            }
+        };
+
+    public static final List<Double []>readPoints(Reader reader)
+    throws IOException
+    {
+        Map<Double, Double> map = new TreeMap<Double, Double>(EPS_CMP);
+
+        BufferedReader input = new BufferedReader(reader);
+
+        String line;
+        while ((line = input.readLine()) != null) {
+            if ((line = line.trim()).length() == 0 || line.startsWith("#")) {
+                continue;
+            }
+
+            String [] parts = line.split("\\s+");
+
+            if (parts.length < 2) {
+                continue;
+            }
+
+            try {
+                Double x = Double.valueOf(parts[0]);
+                Double y = Double.valueOf(parts[1]);
+
+                Double old = map.put(x, y);
+
+                if (old != null) {
+                    System.err.println("duplicate x: " + x);
+                }
+            }
+            catch (NumberFormatException nfe) {
+                nfe.printStackTrace();
+            }
+        }
+
+        List<Double []> list = new ArrayList<Double []>(map.size());
+
+        for (Map.Entry<Double, Double> entry: map.entrySet()) {
+            list.add(new Double [] { entry.getKey(), entry.getValue() });
+        }
+
+        return list;
+    }
+
+    public static void main(String [] args) {
+
+        Function function = FunctionFactory
+            .getInstance()
+            .getFunction(FUNCTION_NAME);
+
+        if (function == null) {
+            System.err.println("Cannot find function '" + FUNCTION_NAME + "'.");
+            System.exit(1);
+        }
+
+        List<Double []> points = null;
+
+        try {
+            points = readPoints(new InputStreamReader(System.in));
+        }
+        catch (IOException ioe) {
+            ioe.printStackTrace();
+            System.exit(1);
+        }
+
+        LevenbergMarquardtOptimizer lmo = new LevenbergMarquardtOptimizer();
+
+        CurveFitter cf = new CurveFitter(lmo);
+
+        for (Double [] point: points) {
+            cf.addObservedPoint(point[0], point[1]);
+        }
+
+        double [] parameters = null;
+
+        try {
+            parameters = cf.fit(function, function.getInitialGuess());
+        }
+        catch (MathException me) {
+            me.printStackTrace();
+            System.exit(1);
+        }
+
+        String [] parameterNames = function.getParameterNames();
+
+        for (int i = 0; i < parameterNames.length; ++i) {
+            System.err.println(parameterNames[i] + ": " + parameters[i]);
+        }
+    }
+}
+// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :