Identity matrix in C#

Question: Program to check whether the matrix is Identity or not.

A matrix is Said to be identity matrix if it satisfied following criteria:

• Matrix is Square matrix
• Element of diagonal are all 1.
• Rest element of matrix excluding diagonal are all zero.

 Identity Matrix : 

We denote the identity matrix of order n. When order is clear by context, we simply write it as I.

For example: 

In the above A, B, C are Identity matrix of order 1, 2, 3 respectively.
Observe that Scalar Matrix is an identity matrix when  k = 1. But every Identity matrix is clearly a scalar matrix.

Code Snippet:

1. using System;  
2.   
3. public class IdtMat  
4. {  
5.    public static void Main()  
6.    {  
7.       int i, row, col;  
8.        
9.       Console.Write("\nEnter the no. of rows and cols : ");  
10.       i = Convert.ToInt32(Console.ReadLine());  
11.       int[,] matA = new int[i, i];       
12.       Console.WriteLine("\nEnter the Elements in Matrix:\n");  
13.   
14.       for(row = 0; row < i; row++)  
15.       {  
16.          for(col = 0; col < i; col++)  
17.          {  
18.             Console.Write("A[{0}, {1}] = ", row, col);   
19.             matA[row,col]= Convert.ToInt32(Console.ReadLine());  
20.          }  
21.          Console.WriteLine();  
22.       }  
23.   
24.       Console.WriteLine("Matrix A:\n");  
25.   
26.       for(row = 0; row < i; row++)  
27.       {  
28.          for(col = 0; col < i; col++)  
29.            Console.Write("{0, 2} ", matA[row,col]);  
30.          Console.WriteLine();  
31.       }  
32.   
33.       bool isIdentity = true;  
34.   
35.       for(row = 0; row < i; row++)  
36.       {  
37.          for(col = 0; col < i; col++)  
38.          {  
39.             if ((row == col && matA[row, col] != 1) ||  
40.                 (row != col && matA[row, col] != 0))  
41.             {  
42.                isIdentity = false;  
43.                break;  
44.             }     
45.          }  
46.       }  
47.         
48.       if(isIdentity)  
49.       {   
50.          Console.WriteLine("\nIdentity Matrix");  
51.       }  
52.       else  
53.       {  
54.          Console.WriteLine("\nNot an Identity Matrix");  
55.       }  
56.   
57.       Console.ReadKey(true);  
58.    }  
59. } 

** Complete code

Description:

In the above code first of all we declare some variable row, col, i to read and write the matrix we take a 2-dimensional array of matA and a bool variable which is initialize to true.

First of all we enter the no. of row and column in Line 9,10,11 . After that we enter the element of matrix and print the matrix.

1.     for(row = 0; row < i; row++)  
2.       {  
3.          for(col = 0; col < i; col++)  
4.          {  
5.             if ((row == col && matA[row, col] != 1) ||  
6.                 (row != col && matA[row, col] != 0))  
7.             {  
8.                isIdentity = false;  
9.                break;  
10.             }     
11.          }  
12.       }  

In the above piece of code we design the logic of Identity matrix if i and j equal to each other i.e (1,1) (2,2) (3,3) then "1" is print or if i and j not equals to each other and if elements of matrix not equals to 0 than ths IsIdentity bool value changed to false.

Screenshot of output:

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Types of matrix in C#