Java/src/main/java/com/thealgorithms/maths/Gaussian.java at master · tyb/Java · GitHub

History

67 lines (56 loc) · 2.07 KB

Raw

package com.thealgorithms.maths;

import java.util.ArrayList;

public class Gaussian {

public static ArrayList<Double> gaussian(int mat_size, ArrayList<Double> matrix) {

ArrayList<Double> answerArray = new ArrayList<Double>();

int i, j = 0;

double[][] mat = new double[mat_size + 1][mat_size + 1];

double[][] x = new double[mat_size][mat_size + 1];

// Values from arraylist to matrix

for (i = 0; i < mat_size; i++) {

for (j = 0; j <= mat_size; j++) {

mat[i][j] = matrix.get(i);

}

mat = gaussianElimination(mat_size, i, mat);

answerArray = valueOfGaussian(mat_size, x, mat);

return answerArray;

}

// Perform Gaussian elimination

public static double[][] gaussianElimination(int mat_size, int i, double[][] mat) {

int step = 0;

for (step = 0; step < mat_size - 1; step++) {

for (i = step; i < mat_size - 1; i++) {

double a = (mat[i + 1][step] / mat[step][step]);

for (int j = step; j <= mat_size; j++) {

mat[i + 1][j] = mat[i + 1][j] - (a * mat[step][j]);

}

return mat;

}

// calculate the x_1, x_2,... values of the gaussian and save it in an arraylist.

public static ArrayList<Double> valueOfGaussian(int mat_size, double[][] x, double[][] mat) {

ArrayList<Double> answerArray = new ArrayList<Double>();

int i, j;

for (i = 0; i < mat_size; i++) {

for (j = 0; j <= mat_size; j++) {

x[i][j] = mat[i][j];

}

for (i = mat_size - 1; i >= 0; i--) {

double sum = 0;

for (j = mat_size - 1; j > i; j--) {

x[i][j] = x[j][j] * x[i][j];

sum = x[i][j] + sum;

}

if (x[i][i] == 0) {

x[i][i] = 0;

} else {

x[i][i] = (x[i][mat_size] - sum) / (x[i][i]);

}

answerArray.add(x[i][j]);

}

return answerArray;

}

Java/src/main/java/com/thealgorithms/maths/Gaussian.java at master · tyb/Java · GitHub

Expand file tree

Breadcrumbs

Gaussian.java

Latest commit

History

Breadcrumbs

Gaussian.java

File metadata and controls