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diff --git a/src/main/java/com/jsyn/unitgen/FunctionEvaluator.java b/src/main/java/com/jsyn/unitgen/FunctionEvaluator.java
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+/*
+ * Copyright 2009 Phil Burk, Mobileer Inc
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/**
+ * Aug 26, 2009
+ * com.jsyn.engine.units.TunableFilter.java 
+ */
+
+package com.jsyn.unitgen;
+
+import com.jsyn.data.Function;
+import com.jsyn.ports.UnitFunctionPort;
+import com.jsyn.ports.UnitInputPort;
+
+/**
+ * Convert an input value to an output value. The Function is typically implemented by looking up a
+ * value in a DoubleTable. But other implementations of Function can be used. Input typically ranges
+ * from -1.0 to +1.0.
+ * 
+ * <pre>
+ * <code>
+ *     // A unit that will lookup the function.
+ * 	FunctionEvaluator shaper = new FunctionEvaluator();
+ * 	synth.add( shaper );
+ * 	shaper.start();
+ * 	// Define a custom function.
+ * 	Function cuber = new Function()
+ * 	{
+ * 		public double evaluate( double x )
+ * 		{
+ * 			return x * x * x;
+ * 		}
+ * 	};
+ * 	shaper.function.set(cuber);
+ * 
+ * 	shaper.input.set( 0.5 );
+ *  </code>
+ * </pre>
+ * 
+ * @author Phil Burk (C) 2009 Mobileer Inc
+ * @see Function
+ */
+public class FunctionEvaluator extends UnitFilter {
+    public UnitInputPort amplitude;
+    public UnitFunctionPort function;
+
+    public FunctionEvaluator() {
+        addPort(amplitude = new UnitInputPort("Amplitude", 1.0));
+        addPort(function = new UnitFunctionPort("Function"));
+    }
+
+    @Override
+    public void generate(int start, int limit) {
+        double[] inputs = input.getValues();
+        double[] amplitudes = amplitude.getValues();
+        double[] outputs = output.getValues();
+        Function functionObject = function.get();
+
+        for (int i = start; i < limit; i++) {
+            outputs[i] = functionObject.evaluate(inputs[i]) * amplitudes[i];
+        }
+
+    }
+}