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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;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.Vector;
+
+/**
+ * Polynomial<br>
+ * Implement polynomial using Vector as coefficient holder. Element index is power of X, value at a
+ * given index is coefficient.<br>
+ * <br>
+ *
+ * @author Nick Didkovsky, (C) 1997 Phil Burk and Nick Didkovsky
+ */
+
+public class Polynomial {
+
+ private static final Logger LOGGER = LoggerFactory.getLogger(Polynomial.class);
+
+ private final Vector terms;
+
+ // TODO: Does this need to exist?
+ static class DoubleHolder {
+ double value;
+
+ public DoubleHolder(double val) {
+ value = val;
+ }
+
+ public double get() {
+ return value;
+ }
+
+ public void set(double val) {
+ value = val;
+ }
+ }
+
+ /** create a polynomial with no terms */
+ public Polynomial() {
+ terms = new Vector();
+ }
+
+ /** create a polynomial with one term of specified constant */
+ public Polynomial(double c0) {
+ this();
+ appendTerm(c0);
+ }
+
+ /** create a polynomial with two terms with specified coefficients */
+ public Polynomial(double c1, double c0) {
+ this(c0);
+ appendTerm(c1);
+ }
+
+ /** create a polynomial with specified coefficients */
+ public Polynomial(double c2, double c1, double c0) {
+ this(c1, c0);
+ appendTerm(c2);
+ }
+
+ /** create a polynomial with specified coefficients */
+ public Polynomial(double c3, double c2, double c1, double c0) {
+ this(c2, c1, c0);
+ appendTerm(c3);
+ }
+
+ /** create a polynomial with specified coefficients */
+ public Polynomial(double c4, double c3, double c2, double c1, double c0) {
+ this(c3, c2, c1, c0);
+ appendTerm(c4);
+ }
+
+ /**
+ * Append a term with specified coefficient. Power will be next available order (ie if the
+ * polynomial is of order 2, appendTerm will supply the coefficient for x^3
+ */
+ public void appendTerm(double coefficient) {
+ terms.addElement(new DoubleHolder(coefficient));
+ }
+
+ /** Set the coefficient of given term */
+ public void setTerm(double coefficient, int power) {
+ // If setting a term greater than the current order of the polynomial, pad with zero terms
+ int size = terms.size();
+ if (power >= size) {
+ for (int i = 0; i < (power - size + 1); i++) {
+ appendTerm(0);
+ }
+ }
+ ((DoubleHolder) terms.elementAt(power)).set(coefficient);
+ }
+
+ /**
+ * Add the coefficient of given term to the specified coefficient. ex. addTerm(3, 1) add 3x to a
+ * polynomial, addTerm(4, 3) adds 4x^3
+ */
+ public void addTerm(double coefficient, int power) {
+ setTerm(coefficient + get(power), power);
+ }
+
+ /** @return coefficient of nth term (first term=0) */
+ public double get(int power) {
+ if (power >= terms.size())
+ return 0.0;
+ else
+ return ((DoubleHolder) terms.elementAt(power)).get();
+ }
+
+ /** @return number of terms in this polynomial */
+ public int size() {
+ return terms.size();
+ }
+
+ /**
+ * Add two polynomials together
+ *
+ * @return new Polynomial that is the sum of p1 and p2
+ */
+ public static Polynomial plus(Polynomial p1, Polynomial p2) {
+ Polynomial sum = new Polynomial();
+ for (int i = 0; i < Math.max(p1.size(), p2.size()); i++) {
+ sum.appendTerm(p1.get(i) + p2.get(i));
+ }
+ return sum;
+ }
+
+ /**
+ * Subtract polynomial from another. (First arg - Second arg)
+ *
+ * @return new Polynomial p1 - p2
+ */
+ public static Polynomial minus(Polynomial p1, Polynomial p2) {
+ Polynomial sum = new Polynomial();
+ for (int i = 0; i < Math.max(p1.size(), p2.size()); i++) {
+ sum.appendTerm(p1.get(i) - p2.get(i));
+ }
+ return sum;
+ }
+
+ /**
+ * Multiply two Polynomials
+ *
+ * @return new Polynomial that is the product p1 * p2
+ */
+
+ public static Polynomial mult(Polynomial p1, Polynomial p2) {
+ Polynomial product = new Polynomial();
+ for (int i = 0; i < p1.size(); i++) {
+ for (int j = 0; j < p2.size(); j++) {
+ product.addTerm(p1.get(i) * p2.get(j), i + j);
+ }
+ }
+ return product;
+ }
+
+ /**
+ * Multiply a Polynomial by a scaler
+ *
+ * @return new Polynomial that is the product p1 * p2
+ */
+
+ public static Polynomial mult(double scaler, Polynomial p1) {
+ Polynomial product = new Polynomial();
+ for (int i = 0; i < p1.size(); i++) {
+ product.appendTerm(p1.get(i) * scaler);
+ }
+ return product;
+ }
+
+ /** Evaluate this polynomial for x */
+ public double evaluate(double x) {
+ double result = 0.0;
+ for (int i = 0; i < terms.size(); i++) {
+ result += get(i) * Math.pow(x, i);
+ }
+ return result;
+ }
+
+ @Override
+ public String toString() {
+ String s = "";
+ if (size() == 0)
+ s = "empty polynomial";
+ boolean somethingPrinted = false;
+ for (int i = size() - 1; i >= 0; i--) {
+ if (get(i) != 0.0) {
+ if (somethingPrinted)
+ s += " + ";
+ String coeff = "";
+ // if (get(i) == (int)(get(i)))
+ // coeff = (int)(get(i)) + "";
+ if ((get(i) != 1.0) || (i == 0))
+ coeff += get(i);
+ if (i == 0)
+ s += coeff;
+ else {
+ String power = "";
+ if (i != 1)
+ power = "^" + i;
+ s += coeff + "x" + power;
+ }
+ somethingPrinted = true;
+ }
+ }
+ return s;
+ }
+
+ public static void main(String[] args) {
+ Polynomial p1 = new Polynomial();
+ LOGGER.debug("p1=" + p1);
+ Polynomial p2 = new Polynomial(3);
+ LOGGER.debug("p2=" + p2);
+ Polynomial p3 = new Polynomial(2, 3);
+ LOGGER.debug("p3=" + p3);
+ Polynomial p4 = new Polynomial(1, 2, 3);
+ LOGGER.debug("p4=" + p4);
+ LOGGER.debug("p4*5=" + Polynomial.mult(5.0, p4));
+
+ LOGGER.debug("{}", p4.evaluate(10));
+
+ LOGGER.debug("{}", Polynomial.plus(p4, p1));
+ LOGGER.debug("{}", Polynomial.minus(p4, p3));
+ p4.setTerm(12.2, 5);
+ LOGGER.debug("{}", p4);
+ p4.addTerm(0.8, 5);
+ LOGGER.debug("{}", p4);
+ p4.addTerm(0.8, 7);
+ LOGGER.debug("{}", p4);
+ LOGGER.debug("{}", Polynomial.mult(p3, p2));
+ LOGGER.debug("{}", Polynomial.mult(p3, p3));
+ LOGGER.debug("{}", Polynomial.mult(p2, p2));
+
+ Polynomial t2 = new Polynomial(2, 0, -1); // 2x^2-1, Chebyshev Polynomial of order 2
+ Polynomial t3 = new Polynomial(4, 0, -3, 0); // 4x^3-3x, Chebyshev Polynomial of order 3
+ // Calculate Chebyshev Polynomial of order 4 from relation Tk+1(x) = 2xTk(x) - Tk-1(x)
+ Polynomial t4 = Polynomial.minus(Polynomial.mult(t3, (new Polynomial(2, 0))), t2);
+ LOGGER.debug(t2 + "\n" + t3 + "\n" + t4);
+ // com.softsynth.jmsl.util
+
+ }
+}