Matrix multiplication

This program show how to multiply two matrices A & B into a third matrix C. Here the matrix having 3 rows and 3 columns (3x3). As given below, inputMatrix( ) and displayMatrix( ) are two static methods which are used to read and display the matrix values respectively. java.util.Scanner class is used to read values from keyboard at runtime.



PROGRAM
import java.util.Scanner;

public class MatrixMultiplication {

 // Method to read matrix elements
 public static void inputMatrix(int temp[][]) {
  Scanner s = new Scanner(System.in);
  for(int i=0;i<3; i++) {
   for(int j=0; j<3; j++) {
    temp[i][j] = s.nextInt();
   }
  }
 }
 
 // Method to display matrix elements
 public static void displayMatrix(int temp[][]) {
  for(int i=0;i<3; i++) {
   for(int j=0; j<3; j++) {
    System.out.print(temp[i][j] + " ");
   }
   System.out.println("");
  }
 }
 
 public static void main(String[] args) {

  int a[][] = new int[3][3];  // First matrix
  int b[][] = new int[3][3];  // Second matrix
  int c[][] = new int[3][3];  // Final matrix which is to store multiplication result
  
  // Input Matrix A elements
  System.out.println("Enter the 9 numbers for first matrix (3x3)...");
  inputMatrix(a);
  
  // Input Matrix B elements
  System.out.println("Enter the 9 numbers for second matrix (3x3)...");
  inputMatrix(b);
  
  // Multiplication logic goes here
  for(int i=0; i<3; i++) {
   for(int j=0; j<3; j++) {
    for(int k=0; k<3; k++) {
     c[i][j] = c[i][j] + (a[i][k] * b[k][j]);
    }
   }
  }
  
  System.out.println("Matrix A is ...");
  displayMatrix(a);
  
  System.out.println("Matrix B is ...");
  displayMatrix(b);
  
  System.out.println("After multiplication Matrix C is ...");
  displayMatrix(c);
 }
}
OUTPUT 
C:\>javac MatrixMultiplication.java
C:\>java MatrixMultiplication
Enter the 9 numbers for first matrix (3x3)...
1 2 3
4 5 6
7 8 9
Enter the 9 numbers for second matrix (3x3)...
1 2 3 
4 5 6
7 8 9
Matrix A is ...
1 2 3 
4 5 6 
7 8 9 
Matrix B is ...
1 2 3 
4 5 6 
7 8 9 
After multiplication Matrix C is ...
30 36 42 
66 81 96 
102 126 150

Popular posts from this blog

Program to define a class 'employee' with data members as empid, name and salary. Accept data for 5 objects using Array of objects and print it.

This program demonstrates you the array of objects.  Array of object  is the collection of objects of the same class. The given syntax will define an array of reference therefore assign object to individual reference in the array to declare the array of object. The syntax to define array of object is: <class-name> <array-name> [size]; For example, the following statement will define an array of object having size 6 references to the class  Box . Box b[6]; For creating an array of objects (allocating memory) you have to write down the following statements for (int i=0; i<6; i++) { b[i] = new Box(); // Assigning object to individual reference in the array. } PROGRAM import java.util.Scanner; public class Employee { int empid; String name; float salary; public void getInput() { Scanner in = new Scanner(System.in); System.out.print("Enter the empid :: "); empid = in.nextInt(); System.out.print("Enter the name :: ");
Read more

Define a class Student with four data members such as name, roll no.,sub1, and sub2. Define appropriate methods to initialize and display the values of data members. Also calculate total marks and percentage scored by student.

In this program, first we first create a class  Student  which have data members  name, roll_no, sub1, sub2  and one method to read data here  getdata( )  method and show the result here  show( )  method. We have used  java.io.BufferedReader  class to read data from keyboard at runtime. Then we have created an object of Student class in  StudentDemo  class and called the methods of Student class. When you compile the code using  javac StudentDemo.java  command two .class files will be created which are  Student.class  and  StudentDemo.class , this has the advantage that you can reuse your .class file somewhere in other projects without compiling the code again. You can create as many classes as you want but writing many classes in a single file is not recommended as it makes code difficult to read rather you can create single file for every class. You can also group classes in packages for easily managing your code. PROGRAM import java.lang.*; import java.io.*; class Student
Read more