HW 6 attempt 2

/**
 * Nate Wheeler
 * compsci 220
 * Hw 6
 * Email: nrwheel@student.stcc.edu
 *
 */

import java.util.Arrays;
import java.util.Scanner;

public class Hw6 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        System.out.println("Enter a11, a12, a13, a21, a22, a23, a31, a32, a33: ");
        Scanner input = new Scanner(System.in);
        double[][] matrix = new double[3][3];
        for (int i = 0; i < matrix.length; i++) {
            for (int j = 0; j < matrix[i].length; j++) {
                matrix[i][j] = input.nextDouble();
            }
        }
        System.out.println("");
        System.out.println(Arrays.deepToString(matrix));
        if (inverse(matrix) == null)
            System.out.println("No inverse matrix");
        else
            System.out.println(Arrays.deepToString(inverse(matrix)));

    }

    public static double[][] inverse(double[][] a) {
        double determinate;
        determinate = a[0][0] * a[1][1] * a[2][2] + a[2][1] * a[0][1] * a[1][2] + a[0][2] * a[1][0] * a[2][0]
                - a[0][2] * a[1][1] * a[2][0] - a[0][0] * a[1][2] * a[2][1] - a[2][2] * a[1][0] * a[0][1];
        if (determinate == 0) {
            return null;
        }
        // first row
        a[0][0] = a[1][1] * a[2][2] - a[1][2] * a[2][1];
        a[0][1] = a[0][2] * a[2][1] - a[0][1] * a[2][2];
        a[0][2] = a[0][1] * a[1][2] - a[0][2] * a[1][1];
        // second row
        a[1][0] = a[1][2] * a[2][0] - a[1][0] * a[2][2];
        a[1][1] = a[0][0] * a[2][2] - a[0][2] * a[2][0];
        a[1][2] = a[0][2] * a[1][0] - a[0][0] * a[1][0];
        // third row
        a[2][0] = a[1][0] * a[2][1] - a[1][1] * a[2][0];
        a[2][1] = a[0][1] * a[2][0] - a[0][0] * a[2][1];
        a[2][1] = a[0][0] * a[1][1] - a[0][1] * a[1][0];

        for (int i = 0; i < a.length; i++) {
            for (int j = 0; j < a[i].length; j++) {
                a[i][j] = 1 / determinate * a[i][j];
            }
        }
        return a;
    }

}