--- a/flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/fitting/Exp.java	Mon Jun 25 19:13:16 2012 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/math/fitting/Exp.java	Tue Jun 26 06:33:37 2012 +0000
@@ -10,18 +10,21 @@
         public de.intevation.flys.artifacts.math.Function
             instantiate(double [] parameters)
         {
-            final double m = parameters[0];
-            final double a = parameters[1];
+                  double m     = parameters[0];
+            final double a     = parameters[1];
+            final double logam = Math.log(a)*m;
 
             return new de.intevation.flys.artifacts.math.Function() {
                 @Override
                 public double value(double Q) {
-                    return Math.pow(a, Q)*Math.log(a)*m;
+                    return Math.pow(a, Q)*logam;
                 }
             };
         }
     };
 
+    public static final Function INSTANCE = new Exp();
+
     public Exp() {
         super(
             "exp",
@@ -47,5 +50,10 @@
     public Derivative getDerivative() {
         return DERIVATIVE;
     }
+
+    @Override
+    public Function getInverse() {
+        return InvExp.INSTANCE;
+    }
 }
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