Identity Matrices

Author: sathishmepco

InterviewPrograms/src/com/java/matrix/IdentityMatrix.java

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+package com.java.matrix;
+
+/*
+ * Identity Matrix
+ * 
+ * If a matrix is a Identity matrix then it should 
+ * follow all the conditions
+ * 1. It should be square matrix row == column
+ * 2. All the elements of main diagonal should be 1
+ * 3. Rest of the elements should be 0.
+ * 
+ * If any of the above conditions are not satisfied
+ * then the matrix is not Identity Matrix.
+ * 
+ * Examples of Identity matrix
+ * 1 0 0 
+ * 0 1 0
+ * 0 0 1
+ * 
+ * 1 0 0 0
+ * 0 1 0 0
+ * 0 0 1 0
+ * 0 0 0 1
+ * 
+ * NOT Identity matrix
+ * 1 2
+ * 3 4
+ * 
+ * 1 1 1
+ * 1 0 1
+ * 1 1 1
+ * 
+ * 1 0 0
+ * 0 1 0
+ *  
+ */
+public class IdentityMatrix {
+	public static void main(String[] args) {
+		int matrix[][] = {
+				{1,0,0,0},
+				{0,1,0,0},
+				{0,0,1,0},
+				{0,0,0,1}
+				};
+/*		int matrix[][] = {
+				{1,0,0},
+				{0,1,0},
+				{0,0,1}
+				};*/
+		int row = 4;
+		int col = 4;
+		
+		//row and col should be same to make square matrix
+		if(row != col){
+			System.out.println("Given matrix is NOT a Identity Matrix");
+			return;
+		}
+		
+		//main diagonal elements should be 1
+		for(int i=0;i<row;i++)
+			if(matrix[i][i] != 1){
+				System.out.println("Given matrix is NOT a Identity Matrix");
+				return;
+			}
+				
+		//rest of the elements should be 0
+		for(int i=0;i<row;i++)
+			for(int j=0;j<col;j++)
+				if(i != j && matrix[i][j] != 0){
+					System.out.println("Given matrix is NOT a Identity Matrix");
+					return;
+				}
+		//if all the 3 conditions are satisfied
+		//Given matrix is Identity Matrix
+		
+		System.out.println("Given matrix is a Identity Matrix");
+	}
+}
+/*
+	INPUT
+	matrix[][] = {
+				{1,0,0,0},
+				{0,1,0,0},
+				{0,0,1,0},
+				{0,0,0,1}
+				};
+	OUTPUT
+	Given matrix is a Identity Matrix
+	
+	INPUT
+	matrix[][] = {
+				{1,0,0},
+				{0,1,0},
+				{0,0,1},
+				};
+	OUTPUT
+	Given matrix is a Identity Matrix
+
+	INPUT
+	matrix[][] = {
+				{1,1,1},
+				{0,1,1},
+				{1,0,1},
+				};
+	OUTPUT
+	Given matrix is NOT a Identity Matrix
+	
+	INPUT
+	matrix[][] = {
+				{1,0,0},
+				{0,1,0}
+				};
+	OUTPUT
+	Given matrix is NOT a Identity Matrix
+*/