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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));
}
}
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