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diff --git a/src/com/jsyn/data/Spectrum.java b/src/com/jsyn/data/Spectrum.java
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+/*
+ * Copyright 2013 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.data;
+
+import com.jsyn.unitgen.SpectralFFT;
+import com.jsyn.unitgen.SpectralIFFT;
+import com.jsyn.unitgen.SpectralProcessor;
+
+/**
+ * Complex spectrum with real and imaginary parts. The frequency associated with each bin of the
+ * spectrum is:
+ * 
+ * <pre>
+ * frequency = binIndex * sampleRate / size
+ * </pre>
+ * 
+ * Note that the upper half of the spectrum is above the Nyquist frequency. Those frequencies are
+ * mirrored around the Nyquist frequency. Note that this spectral API is experimental and may change
+ * at any time.
+ * 
+ * @author Phil Burk (C) 2013 Mobileer Inc
+ * @version 016
+ * @see SpectralFFT
+ * @see SpectralIFFT
+ * @see SpectralProcessor
+ */
+public class Spectrum {
+    private double[] real;
+    private double[] imaginary;
+    public static final int DEFAULT_SIZE_LOG_2 = 9;
+    public static final int DEFAULT_SIZE = 1 << DEFAULT_SIZE_LOG_2;
+
+    public Spectrum() {
+        this(DEFAULT_SIZE);
+    }
+
+    public Spectrum(int size) {
+        setSize(size);
+    }
+
+    public double[] getReal() {
+        return real;
+    }
+
+    public double[] getImaginary() {
+        return imaginary;
+    }
+
+    /**
+     * If you change the size of the spectrum then the real and imaginary arrays will be
+     * reallocated.
+     * 
+     * @param size
+     */
+    public void setSize(int size) {
+        if ((real == null) || (real.length != size)) {
+            real = new double[size];
+            imaginary = new double[size];
+        }
+    }
+
+    public int size() {
+        return real.length;
+    }
+
+    /**
+     * Copy this spectrum to another spectrum of the same length.
+     * 
+     * @param destination
+     */
+    public void copyTo(Spectrum destination) {
+        assert (size() == destination.size());
+        System.arraycopy(real, 0, destination.real, 0, real.length);
+        System.arraycopy(imaginary, 0, destination.imaginary, 0, imaginary.length);
+    }
+
+    public void clear() {
+        for (int i = 0; i < real.length; i++) {
+            real[i] = 0.0;
+            imaginary[i] = 0.0;
+        }
+    }
+}