Java Gauss gaussian(double[][] A, double[] b)

Description

GaussianElimination

License

Open Source License

Parameter

Parameter	Description
A	the x matrix
b	the y matrix

Return

coefficients

Declaration

static double[] gaussian(double[][] A, double[] b) 

Method Source Code

//package com.java2s;
/*/*from  ww w  .jav a 2 s  . com*/
 * Copyright Yi Xiao. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are
 * permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice, this list
 *   of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright notice, this
 *   list of conditions and the following disclaimer listed in this license in the
 *   documentation and/or other materials provided with the distribution.
 *
 * - Neither the name of the copyright holders nor the names of its contributors may
 *   be used to endorse or promote products derived from this software without specific
 *   prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

public class Main {
    /**
     * GaussianElimination
     *
     * @param A
     *            the x matrix
     * @param b
     *            the y matrix
     * @return coefficients
     */
    static double[] gaussian(double[][] A, double[] b) {
        int N = b.length;
        // double EPSILON = 1e-10;

        for (int p = 0; p < N; p++) {

            // find pivot row and swap
            int max = p;
            for (int i = p + 1; i < N; i++) {
                if (Math.abs(A[i][p]) > Math.abs(A[max][p])) {
                    max = i;
                }
            }
            double[] temp = A[p];
            A[p] = A[max];
            A[max] = temp;
            double t = b[p];
            b[p] = b[max];
            b[max] = t;

            // singular or nearly singular
            /*
             * if (Math.abs(A[p][p]) <= EPSILON) { throw new
             * RuntimeException("Matrix is singular or nearly singular"); }
             */

            // pivot within A and b
            for (int i = p + 1; i < N; i++) {
                double alpha = A[i][p] / A[p][p];
                b[i] -= alpha * b[p];
                for (int j = p; j < N; j++) {
                    A[i][j] -= alpha * A[p][j];
                }
            }
        }

        // back substitution
        double[] x = new double[N];
        for (int i = N - 1; i >= 0; i--) {
            double sum = 0.0;
            for (int j = i + 1; j < N; j++) {
                sum += A[i][j] * x[j];
            }
            x[i] = (b[i] - sum) / A[i][i];
        }
        return x;
    }
}

Related

1. gaussian(double mu, double sigma, double x)
2. gaussian(double mu, double sigma, double x)
3. gaussian(double t)
4. gaussian(double x, double sigma)
5. gaussian(double[] d, double sigma, double mean)
6. gaussian(float x, float mean, float sd)
7. gaussian(int size, double sigma)
8. gaussianBlur(int[][] pixels, float sigma)
9. gaussianDensity(double x, double mean, double standardDeviation)