C++ program to check whether a matrix is scalar or not

In this article, we will learn how to check whether a given matrix is scalar or not in C++. A square matrix is said to a scalar if all the diagonal elements of the matrix are equal to each other and non-diagonal elements are equal to zero.

Examples

Input: matrix = {{2, 0, 0, 0},
                 {0, 2, 0, 0},
                 {0, 0, 2, 0},
                 {0, 0, 0, 2}}
Output: Scalar matrix

Input: matrix = {{1, 2, 0, 0},
                 {2, 0, 0, 0},
                 {2, 0, 0, 0},
                 {1, 4, 0, 0}}
Output: Non-scalar matrix

Check whether a matrix is scalar or not in C++

1. Traverse the matrix using two nested loops and check

• If non-diagonal are not equal to zero then return false
  if (i != j && matrix[i][j] != 0)

2. Now check diagonal elements are equal to each other if equal return true.

#include <bits/stdc++.h>
using namespace std;
#define n 3
// function to check matrix is scalar or not
bool scalar_matrix(int matrix[n][n]){
    // check whether non diagonal elements are equal to zero
    for (int i = 0;i<n;i++){
        for(int j=0;j<n;j++){
            if (i != j && matrix[i][j] != 0)
                return false;
        }
    }
    // check whether diagonal elements are equal to each other.
    for(int i =0;i<n-1;i++)
        if(matrix[i][i] != matrix[i+1][i+1])
            return false;
    return true;
}
int main(){
    int matrix[n][n] = {{5, 0, 0},
                        {0, 5, 0},
                        {0, 0, 5}};
    for (int i = 0;i<n;i++){
        for(int j=0;j<n;j++){
            cout<<matrix[i][j]<<" ";
        }
        cout<<endl;
    }                
    if(scalar_matrix(matrix))
        cout<<"Scalar matrix"<<endl;
    else
        cout<<"Non scalar matrix"<<endl;
    return 0;
}

Output

5 0 0 
0 5 0
0 0 5
Scalar matrix

Also, read

• How to check whether matrix is a singular or not in Python
• Matrix Inversion in C++