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diff --git a/src/com/jsyn/unitgen/SawtoothOscillatorDPW.java b/src/com/jsyn/unitgen/SawtoothOscillatorDPW.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.
+ */
+
+package com.jsyn.unitgen;
+
+/**
+ * Sawtooth DPW oscillator (a sawtooth with reduced aliasing). Based on a paper by Antti Huovilainen
+ * and Vesa Valimaki:
+ * http://www.scribd.com/doc/33863143/New-Approaches-to-Digital-Subtractive-Synthesis
+ * 
+ * @author Phil Burk and Lisa Tolentino (C) 2009 Mobileer Inc
+ */
+public class SawtoothOscillatorDPW extends UnitOscillator {
+    // At a very low frequency, switch from DPW to raw sawtooth.
+    private static final double VERY_LOW_FREQUENCY = 2.0 * 0.1 / 44100.0;
+    private double z1;
+    private double z2;
+
+    @Override
+    public void generate(int start, int limit) {
+        double[] frequencies = frequency.getValues();
+        double[] amplitudes = amplitude.getValues();
+        double[] outputs = output.getValues();
+
+        // Variables have a single value.
+        double currentPhase = phase.getValue();
+
+        for (int i = start; i < limit; i++) {
+            /* Generate raw sawtooth phaser. */
+            double phaseIncrement = convertFrequencyToPhaseIncrement(frequencies[i]);
+            currentPhase = incrementWrapPhase(currentPhase, phaseIncrement);
+
+            /* Square the raw sawtooth. */
+            double squared = currentPhase * currentPhase;
+            // Differentiate using a delayed value.
+            double diffed = squared - z2;
+            z2 = z1;
+            z1 = squared;
+
+            /* Calculate scaling based on phaseIncrement */
+            double pinc = phaseIncrement;
+            // Absolute value.
+            if (pinc < 0.0) {
+                pinc = 0.0 - pinc;
+            }
+
+            double dpw;
+            // If the frequency is very low then just use the raw sawtooth.
+            // This avoids divide by zero problems and scaling problems.
+            if (pinc < VERY_LOW_FREQUENCY) {
+                dpw = currentPhase;
+            } else {
+                dpw = diffed * 0.25 / pinc;
+            }
+
+            outputs[i] = amplitudes[i] * dpw;
+        }
+
+        // Value needs to be saved for next time.
+        phase.setValue(currentPhase);
+    }
+
+}