Java Program to Find the Trace of a Matrix

Write a Java program to find the trace of a matrix using for loop. The trace of a matrix is the sum of its diagonal. In this Java example, we use nested for loop to iterate matrix rows and columns. Next, if(i == j) checks whether it’s a diagonal element and adds that item to trace.

package NumPrograms;

import java.util.Scanner;

public class MatrixTrace1 {
	
	private static Scanner sc;	
	
	public static void main(String[] args) {
		
		int i, j, rows, columns, trace = 0;	
		sc= new Scanner(System.in);	
		
		System.out.print("Enter Matrix Rows and Columns =  ");
		rows = sc.nextInt();
		columns = sc.nextInt();
		
		int[][] Tra_arr = new int[rows][columns];
		
		System.out.println("Please Enter the Matrix Items =  ");
		for(i = 0; i < rows; i++) 
		{
			for(j = 0; j < columns; j++) 
			{
				Tra_arr[i][j] = sc.nextInt();
			}		
		}
		
		for(i = 0; i < rows; i++) 
		{
			for(j = 0; j < columns; j++) 
			{
				if(i == j)
				{
					trace = trace + Tra_arr[i][j];
				}
			}		
		}
		
		System.out.println("\nThe Trace Of the Matrix = " + trace);

	}
}

Java program to find the trace of a matrix using a while loop

package NumPrograms;

import java.util.Scanner;

public class MatrixTrace2 {
	private static Scanner sc;	
	public static void main(String[] args) {
		
		int i, j, rows, columns, trace = 0;	
		sc= new Scanner(System.in);	
		
		System.out.print("Enter Matrix Rows and Columns =  ");
		rows = sc.nextInt();
		columns = sc.nextInt();
		
		int[][] Tra_arr = new int[rows][columns];
		
		System.out.println("Please Enter the Matrix Items =  ");
		i = 0; 
		while(i < rows) 
		{
			j = 0; 
			while(j < columns) 
			{
				Tra_arr[i][j] = sc.nextInt();
				j++;
			}	
			i++;
		}
		
		i = 0; 
		while(i < rows) 
		{
			j = 0; 
			while(j < columns) 
			{
				if(i == j)
				{
					trace = trace + Tra_arr[i][j];
				}
				j++;
			}	
			i++;
		}
		
		System.out.println("\nThe Trace Of the Matrix = " + trace);

	}
}

Enter Matrix Rows and Columns =  3 3
Please Enter the Matrix Items =  
10 20 30
40 50 60
70 80 125

The Trace Of the Matrix = 185

This Java example uses the do while loop to calculate and print the trace of a given matrix.

package NumPrograms;

import java.util.Scanner;

public class MatrixTrace3 {
	private static Scanner sc;	
	public static void main(String[] args) {
		
		int i, j, rows, columns, trace = 0;	
		sc= new Scanner(System.in);	
		
		System.out.print("Enter Matrix Rows and Columns =  ");
		rows = sc.nextInt();
		columns = sc.nextInt();
		
		int[][] Tra_arr = new int[rows][columns];
		
		System.out.println("Please Enter the Matrix Items =  ");
		i = 0; 
		do 
		{
			j = 0; 
			do 
			{
				Tra_arr[i][j] = sc.nextInt();
				if(i == j) 
				{
					trace = trace + Tra_arr[i][j];
				}
			}while(++j < columns);	
		}while(++i < rows);
		
		System.out.println("\nThe Trace Of the Matrix = " + trace);

	}
}

Enter Matrix Rows and Columns =  3 3
Please Enter the Matrix Items =  
19 22 45
77 88 125
13 50 500

The Trace Of the Matrix = 607