#What is the size of Array after operating Matrix Multiplication ?

#Forword

I don't know why i feel this, when i need to use Array in Java, I am confused how to use it.. This document also will handle the matrix multiplication, this document is also for my future use and used for organizing concepts. Surely, When I can't define something difficult, I am endeavoring to organize it, In doing so, I can understand how it works without realizing how can i understand this, I hope this works well !

#Matrix Multiplication

• arr1[R1][C1] * arr2[R2][C2]

Requirement For this matrix multiplication.

when (C1 == R2), matrix multiplication can be operated.

First Matrix Column == Second Matrix Row

If (C1 == R2) {

arr1[R1][C1] * arr2[R2][C2] => resultArray[R1][C2]

}

more specified,

• arr1[3][5] * arr2[2][1]

  \==> Column of arr1 != Row of arr2

  \==> This can't be Operated

• arr1[2][4] * arr2[4][5]

  \==> Column of arr1 == Row of arr2

  \==> resultArr[2][5] (arr1 Row * arr2 Column)

#Code Snippets

public class MatrixMultiplication {

    public static void main(String[] args) {

        int[][] arr1 = {{1,2},{13,15},{17,12}};
        int[][] arr2 = {{2,1,5},{7,3,3}};

        if (arr1[0].length != arr2.length) {
            System.out.println(
                "Number of columns in the first matrix must be equal to"
                    + " the number of rows in the second matrix " 
                    + "for matrix multiplication");

            //if this condition is false => exit main method by using "return;" with error message.
            return;
        }

        int[][] result = new int[arr1.length][arr2[0].length];

        for (int i = 0; i < arr1.length; i++) {
            for (int j = 0; j < arr2[0].length; j++) {
                for (int k = 0; k < arr1[0].length; k++) {
                    result[i][j] += arr1[i][k] * arr2[k][j];
                }
            }
        }

        for (int i = 0; i < result.length; i++) {
            for (int j = 0; j < result[0].length; j++) {
                System.out.println("result[" + i + "][" + j + "] = " 
                + result[i][j] + " ");
            }
        }
        System.out.println();
    }
}

cf) In Java, "return;"

When condition is 'false', it will exit the current method.

it's important to note that return; will only exit the current method, not the entire program.