Pandas multiply column by scalar – Java Program to Find Scalar Multiplication of a Matrix

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Pandas multiply column by scalar: In the previous article, we have discussed Java Program to Sort the elements of a Matrix

In this article we are going to see how we can write a program to find the transpose of a matrix in JAVA language.

Java Program to Find Scalar Multiplication of a Matrix

Matrix multiplication in java: A 3*3 Matrix is having 3 rows and 3 columns where this 3*3 represents the dimension of the matrix. Means there are 3*3 i.e. total 9 elements in a 3*3 Matrix.

Let’s understand it in more simpler way.

                   | A00   A01   A02 |
Matrix A =  | A10   A11   A12 |
                   | A20   A21   A22 | 3*3
  • Matrix A represents a 3*3 matrix.
  • ‘A‘ represents the matrix element
  • ‘Aij‘ represents the matrix element at it’s matrix position/index.
  • ‘i‘ represents the row index
  • ‘j‘ represents the column index
  • Means A00=Aij  where i=0 and j=0,  A01=aij where i=0 and j=1 and like this.
  • Here we have started row value from 0 and column value from 0.

Let’s see different ways to find Scalar Multiplication of a Matrix.

Method-1: Java Program to Find Scalar Multiplication of a Matrix By Static Initialization of Array Elements

Approach:

  • Initialize and declare one array of size 3×3 with elements.
  • Use two for loops to iterate the rows and columns.
  • For each element multiply it with the integer.
  • Print the resultant array.

Program:

import java.io.*;
import java.util.*;

public class matrix
{
    public static void main(String args[])
    {
        // Initializing the 3X3 matrix i.e. 2D array
        int arr[][] = {{7,2,4},{3,2,6},{7,5,6}};
        //resultant matrix
        int res[][] = new int[3][3];
        int row, col, n = 5;
        
        System.out.print("The matrix elements are : ");
        printMatrix(arr);

        // Multiplying the matrix using a constant
        for(row=0;row<3;row++)
            for(col=0;col<3;col++)
                arr[row][col] *= n;

        System.out.print("\nThe matrix after multiplication with : "+n);
        printMatrix(arr);
    }

    // Method to print the matrix
    static void printMatrix(int arr[][])
    {
        int row, col;
        // Loop to print the elements
        for(row=0;row<3;row++)
        {
            // Used for formatting
            System.out.print("\n");
            for(col=0;col<3;col++)
            {
                System.out.print(arr[row][col]+" ");
            }
        }
        System.out.print("\n");
    }

}



Output:

The matrix elements are : 
7 2 2 
4 2 6 
7 2 6

The matrix after multiplication with : 5
35 10 10 
20 10 30 
35 10 30

Method-2: Java Program to Find Scalar Multiplication of a Matrix By Dynamic Initialization of Array Elements

Approach:

  • Declare two arrays of size 3×3. One to hold the original matrix and another to hold the resultant matrix.
  • Ask the user for input of array elements and store them in the one array using two for loops.
  • Ask the user to enter an integer to multiply.
  • Use two for loops to iterate the rows and columns .
  • For each element multiply it with the integer.
  • Print the resultant array.

Program:

import java.util.Scanner;
public class matrix
{
    public static void main(String args[])
    {
        //Scanner class to take input
        Scanner scan = new Scanner(System.in);

        // Initializing the 3X3 matrix i.e. 2D array
        int arr[][] = new int[3][3];
        //for resultant matrix
        int res[][] = new int[3][3];
        int row, col ,n;
        
        // Taking matrix input
        System.out.println("\nEnter matrix elements : ");
        for(row=0;row<3;row++)
            for(col=0;col<3;col++)
                arr[row][col] = scan.nextInt();
            
        // Taking the number input
        System.out.println("Enter a number to multiply : ");
        n = scan.nextInt();

        
        System.out.print("The matrix elements are : ");
        printMatrix(arr);

        // Multiplying the matrix using a constant
        for(row=0;row<3;row++)
            for(col=0;col<3;col++)
                arr[row][col] *= n;

        System.out.print("\nThe matrix after multiplication with : "+n);
        printMatrix(arr);
    }

    // Method to print the matrix
    static void printMatrix(int arr[][])
    {
        int row, col;
        // Loop to print the elements
        for(row=0;row<3;row++)
        {
            // Used for formatting
            System.out.print("\n");
            for(col=0;col<3;col++)
            {
                System.out.print(arr[row][col]+" ");
            }
        }
        System.out.print("\n");
    }

}


Output:

Enter matrix elements : 9 8 3 4 5 6 7 3 8
Enter a number to multiply : 4
The matrix elements are : 
9 8 3 
4 5 6 
7 3 8

The matrix after multiplication with : 4
36 32 12 
16 20 24 
28 12 32

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