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

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=0A01=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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