com.golemgame.util.LinearUtils.java Source code

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Here is the source code for com.golemgame.util.LinearUtils.java

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/*******************************************************************************
 * Copyright 2008, 2009, 2010 Sam Bayless.
 * 
 *     This file is part of Golems.
 * 
 *     Golems is free software: you can redistribute it and/or modify
 *     it under the terms of the GNU General Public License as published by
 *     the Free Software Foundation, either version 3 of the License, or
 *     (at your option) any later version.
 * 
 *     Golems is distributed in the hope that it will be useful,
 *     but WITHOUT ANY WARRANTY; without even the implied warranty of
 *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *     GNU General Public License for more details.
 * 
 *     You should have received a copy of the GNU General Public License
 *     along with Golems. If not, see <http://www.gnu.org/licenses/>.
 ******************************************************************************/
package com.golemgame.util;

import org.apache.commons.math.analysis.PolynomialFunction;

public class LinearUtils {
    public static PolynomialFunction generateTranslatedFunction(double[] coefficients, double translation) {

        if (coefficients.length == 1 || translation == 0) {
            return new PolynomialFunction(coefficients);
        }
        translation = -translation;
        for (int power = 1; power < coefficients.length; power++) {
            if (coefficients[power] != 0) {
                double[] expandedCoefficients = getBinomialTerms(power, 1, translation);
                for (int i = 0; i < power; i++) {
                    expandedCoefficients[i] *= coefficients[power];
                    coefficients[i] += expandedCoefficients[i] * Math.pow(translation, power - i);
                }
            }
        }

        return new PolynomialFunction(coefficients);
    }

    private static double[] getBinomialTerms(int power, double x, double y) {
        double[] coefficients = new double[power + 1];

        //terms are in order of power: x going from largest power to 0, y going from 0 to largest.

        coefficients[0] = 1;

        for (int i = 1; i <= power; i++) {
            double last = coefficients[i - 1];

            coefficients[i] = last * (power - i + 1) / i;

        }

        return coefficients;
    }

}