1 files changed, 253 insertions, 0 deletions
diff --git a/src/com/softsynth/math/Polynomial.java b/src/com/softsynth/math/Polynomial.java
new file mode 100644
index 0000000..8670e97
--- /dev/null
+++ b/src/com/softsynth/math/Polynomial.java
@@ -0,0 +1,253 @@
+/*
+ * 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 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 Vector terms;
+
+    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();
+        System.out.println("p1=" + p1);
+        Polynomial p2 = new Polynomial(3);
+        System.out.println("p2=" + p2);
+        Polynomial p3 = new Polynomial(2, 3);
+        System.out.println("p3=" + p3);
+        Polynomial p4 = new Polynomial(1, 2, 3);
+        System.out.println("p4=" + p4);
+        System.out.println("p4*5=" + Polynomial.mult(5.0, p4));
+
+        System.out.println(p4.evaluate(10));
+
+        System.out.println(Polynomial.plus(p4, p1));
+        System.out.println(Polynomial.minus(p4, p3));
+        p4.setTerm(12.2, 5);
+        System.out.println(p4);
+        p4.addTerm(0.8, 5);
+        System.out.println(p4);
+        p4.addTerm(0.8, 7);
+        System.out.println(p4);
+        System.out.println(Polynomial.mult(p3, p2));
+        System.out.println(Polynomial.mult(p3, p3));
+        System.out.println(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);
+        System.out.println(t2 + "\n" + t3 + "\n" + t4);
+        // com.softsynth.jmsl.util
+
+    }
+}