We were given this program in class yesterday. The original question is here

Write a method to add/subtract two matrices. The header of the method is as follows:

public static double[][] addMatrix(double[][] a, double[][] b

or

public static double[][] subtractMatrix(double[][] a, double[][] b

In order to be add/subtract, the two matrices must have the same dimensions and the same or compatible types of elements. Let c be the resulting matrix. Each element cij is aij + bij. For example, for two 3 * 3 matrices a and b, c is

Write a test program that prompts the user to enter two 3 * 3 matrices and displays their sum or differece. Here is a sample run

the code given is this below. could you please explain what is going on throughout it? I still do not understand it.

Thank you!

package Week4;

import java.util.Scanner;

public class Lab4_1 {

/** * Madison Garnett * Class: CSCI1302 8:30am-10:20am * Lab 4.1 * This lab writes a method to add two matrices. */

//Create Matrix public static double[][] addMatrix(double[][] a, double[][] b) { double[][] result = new double[a.length][a[0].length]; for(int i = 0; i < a.length; ++i) { for(int j = 0; j < a[i].length; ++j) { result[i][j] = a[i][j] + b[i][j]; } } return result; }

//Calculations public static void main(String[] args) { Scanner in = new Scanner(System.in); double[][] matrix1 = new double[3][3]; double[][] matrix2 = new double[3][3];

//Prompt user to enter matrix 1 System.out.print("Enter matrix1: "); for(int i = 0; i < matrix1.length; ++i) { for(int j = 0; j < matrix1[i].length; ++j) { matrix1[i][j] = in.nextDouble(); } }

//Prompt user to enter matrix 2 System.out.print("Enter matrix2: "); for(int i = 0; i < matrix2.length; ++i) { for(int j = 0; j < matrix2[i].length; ++j) { matrix2[i][j] = in.nextDouble(); } } double[][] matrix3 = addMatrix(matrix1, matrix2);

//Outputs System.out.println(" The addition of the matrices is"); double minSum = 0; int minRow = 0; for(int i = 0; i < 3; ++i) { for(int j = 0; j < 3; ++j) { System.out.printf("%5.1f\t", matrix1[i][j]); } if(i == 1) { System.out.printf(" + "); } else { System.out.printf(" "); } for(int j = 0; j < 3; ++j) { System.out.printf("%5.1f\t", matrix2[i][j]); } if(i == 1) { System.out.printf(" = "); } else { System.out.printf(" "); } for(int j = 0; j < 3; ++j) { System.out.printf("%5.1f\t", matrix3[i][j]); } double sum = 0; for(int j = 0; j < 3; ++j) { sum += matrix3[i][j]; } if (i == 0 || sum < minSum) { minSum = sum; } System.out.printf(" "); } } }