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+/*
+ * Copyright 1997 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.softsynth.math;
+
+/**
+ * ChebyshevPolynomial<br>
+ * Used to generate data for waveshaping table oscillators.
+ *
+ * @author Nick Didkovsky (C) 1997 Phil Burk and Nick Didkovsky
+ */
+
+public class ChebyshevPolynomial {
+ static final Polynomial twoX = new Polynomial(2, 0);
+ static final Polynomial one = new Polynomial(1);
+ static final Polynomial oneX = new Polynomial(1, 0);
+
+ /**
+ * Calculates Chebyshev polynomial of specified integer order. Recursively generated using
+ * relation Tk+1(x) = 2xTk(x) - Tk-1(x)
+ *
+ * @return Chebyshev polynomial of specified order
+ */
+ public static Polynomial T(int order) {
+ if (order == 0)
+ return one;
+ else if (order == 1)
+ return oneX;
+ else
+ return Polynomial.minus(Polynomial.mult(T(order - 1), (twoX)), T(order - 2));
+ }
+}