Syntax error How to Check if the Matrix is Diagonal Matrix in Java?

How to Check if the Matrix is Diagonal Matrix in Java?

In Java, Array is an object. It is a non-primitive data type which stores values of similar data type. The matrix in java is nothing but a multi-dimensional array which represents multiple rows and columns.

A matrix having non-zero elements only in the main diagonal (running from the upper left to the lower right) is called as diagonal matrix.

As per the problem statement we have to a matrix and we have to check whether that given matrix is a diagonal matrix or not.

Let's deep dive into this article, to know how it can be done by using Java programming language.

To show you some instances

Instance-1

Given matrix =

21 	0	0
0	25	0
0	0	29

The given matrix is a diagonal matrix because the main diagonal only contains non-zero values and other elements are zeros.

Instance-2

Given matrix =

121 	0	0	432
0	567	0	0
0	0	229	0
176	0	0	343

The given matrix is not a diagonal matrix because with main diagonal some other elements are also containing non-zero values.

Instance-3

Given matrix =

1 	0	0	0	0
0	7	0	0	0
0	0	13	0	0
0	0	0	19	0
0	0	9	0	25

The given matrix is a diagonal matrix because the main diagonal only contains non-zero values and other elements are zeros.

Algorithm

Algorithm-1

  • Step-1 ? Define the matrix as a 2D array.

  • Step-2 ? Check if the matrix is square. If not, set the checkDiagonal flag to false.

  • Step-3 ? Loop over all elements in the matrix. If an off-diagonal element is non-zero, set the checkDiagonal flag to false and break out of both loops using the break statement.

  • Step-4 ? Print whether the matrix is diagonal or not based on the value of the checkDiagonal flag.

Algorithm-2

  • Step-1 ? Define the matrix as a 2D array.

  • Step-2 ? Check if the matrix is square. If not, set the checkDiagonal flag to false.

  • Step-3 ? Use streams to check if any off-diagonal element is non-zero. If so, set the checkDiagonal flag to false.

  • Step-4 ? Use the isEmpty() method to check if the stream is empty. If so, the matrix is diagonal.

  • Step-5 ? Print whether the matrix is diagonal or not based on the value of the checkDiagonal flag.

Multiple Approaches

We have provided the solution in different approaches.

  • By Using Nested for Loop

  • By Using Java Streams

Let's see the program along with its output one by one.

Approach-1: By Using Nested for Loop

In this approach, matrix elements will be initialized in the program. Then as per the algorithm using nested for loop check whether the matrix is a diagonal matrix or not.

Example

public class Main {
   public static void main(String[] args) {
      // Define the matrix
      int[][] inputMatrix = {{1, 0, 0}, {0, 5, 0}, {0, 0, 7}};
      
      // declare a variable to store the boolean values
      boolean checkDiagonal = true;
      if (inputMatrix.length != inputMatrix[0].length) {
         checkDiagonal = false;
      } else {
         for (int i = 0; i < inputMatrix.length; i++) {
            for (int j = 0; j < inputMatrix[0].length; j++) {
               if (i != j && inputMatrix[i][j] != 0) {
                  checkDiagonal = false;
                  break;
               }
            }
            if (!checkDiagonal) {
               break;
            }
         }
      }
      
      // Print the result
      if (checkDiagonal) {
         System.out.println("The matrix is a diagonal matrix");
      } else {
         System.out.println("The matrix is not a diagonal matrix");
      }
   }
}

Output

The matrix is a diagonal matrix

Approach-2: By Using Java Streams

In this approach, matrix elements will be initialized in the program. Then as per the algorithm using java streams check whether the matrix is a diagonal matrix or not.

Example

import java.util.Arrays;
import java.util.stream.IntStream;
public class Main {
   public static void main(String[] args) {
      
      // Define the matrix
      int[][] inputMatrix = {{1, 0, 0}, {0, 5, 5}, {0, 0, 7}};

      // declare a variable to store the boolean values
      boolean checkDiagonal = true;
      if (inputMatrix.length != inputMatrix[0].length) {
         checkDiagonal = false;
      } else {
         checkDiagonal = IntStream.range(0, inputMatrix.length)
            .flatMap(i -> IntStream.range(0, inputMatrix[0].length)
               .filter(j -> i != j && inputMatrix[i][j] != 0))
            .findFirst()
            .isEmpty();
      }

      // Print the result
      if (checkDiagonal) {
         System.out.println("The given matrix is a diagonal matrix");
      } else {
         System.out.println("The given matrix is not a diagonal matrix");
      }
   }
}

Output

The given matrix is not a diagonal matrix

In this article, we explored different approaches to check if the matrix is a diagonal matrix or not by using Java programming language.

Updated on: 2023-05-04T15:55:59+05:30

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