Java Program to Decrement the Matrix Elements by a Specified Number

In this article we are going to see how we can write a program to decrement each element of the matrix by a specified number in JAVA language.

Java Program to Decrement the Matrix Elements by One

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 decrement the Matrix Elements by a specified number.

Method-1: Java Program to Decrement the Matrix Elements by a Specified Number By Static Initialization of Array Elements

Approach:

  • Declare and Initialize an array of 3*3 means main matrix is ready.
  • Declare another resultant array of 3*3 means resultant matrix.
  • Now take two for loops and iterate each element of the main matrix and decrement each element by the specified number.
  • Go on storing each decremented element to the resultant matrix.
  • Print the resultant matrix.

Program:

public class Matrix
{
    public static void main(String args[])
    {

        // Initializing the 3X3 matrix i.e. 2D array
        int arr[][] = {{19,25,32},{40,54,62},{70,20,60}};
        //Resultant matrix
        int resArr[][] = new int[3][3];
        //A number specified 
        int n=4;
        int row, col ;

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

        // Loops to decrement each element of matrix by a specified number
        for(row=0;row<3;row++)
        {
            for(col=0;col<3;col++)
            {
                resArr[row][col] = arr[row][col]-n;
            }   
        }
        
        System.out.print("\nThe matrix after decrementing by "+n+" is : ");
        printMatrix(resArr);
    }

    // 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 is : 
19 25 32 
40 54 62 
70 20 60

The matrix after decrementing by 4 is : 
15 21 28 
36 50 58 
66 16 56

Method-2: Java Program to Decrement the Matrix Elements by a Specified Number By Dynamic Initialization of Array Elements

Approach:

  • Declare an array of 3*3.
  • Take the input of array elements from the user, so now main matrix is ready.
  • Declare another resultant array of 3*3 means resultant matrix.
  • Now take two for loops and iterate each element of the main matrix and decrement each element by the specified number.
  • Go on storing each decremented element to the resultant matrix.
  • Print the resultant matrix.

Program:

import java.util.*;

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];
        
        //Taking  a number input from user 
        //which will be used to decrement matrix
         System.out.println("Enter a number : ");
        int n=scan.nextInt();
        
         //Resultant matrix
        int resArr[][] = new int[3][3];
        int row, col ;
        
        // Taking main matrix input
        System.out.println("Enter matrix elements : ");
        for(row=0;row<3;row++)
            for(col=0;col<3;col++)
                arr[row][col] = scan.nextInt();
      

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

        // Loops to decrement each element of matrix by a specified number
        for(row=0;row<3;row++)
        {
            for(col=0;col<3;col++)
            {
                resArr[row][col] = arr[row][col]-n;
            }   
        }
        
        System.out.print("\nThe matrix after decrementing by "+n+" is : ");
        printMatrix(resArr);
    }

    // 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 a number : 10
Enter matrix elements : 100 100 100 100 100 100 100 100 100
The matrix is : 
100 100 100 
100 100 100 
100 100 100

The matrix after decrementing by 10 is : 
90 90 90 
90 90 90 
90 90 90

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