Javascript Program to check idempotent matrix

// Javascript program to check given matrix 
// is idempotent matrix or not.
let N = 3;

// Function for matrix multiplication.
function multiply(mat, res) {
    for (let i = 0; i < N; i++) {
        for (let j = 0; j < N; j++) {
            res[i][j] = 0;
            for (let k = 0; k < N; k++)
                res[i][j] += mat[i][k] * mat[k][j];
        }
    }
    return res;
}

// Function to check idempotent
// property of matrix.
function checkIdempotent(mat) {

    // Calculate multiplication of matrix
    // with itself and store it into res.
    let res = Array.from(Array(N), () => Array(N).fill(0));
    res = multiply(mat, res);

    for (let i = 0; i < N; i++) {
        for (let j = 0; j < N; j++) {
            if (mat[i][j] != res[i][j])
                return false;
        }
    }
    return true;
}

// Driver code
let mat = [[2, -2, -4],
[-1, 3, 4],
[1, -2, -3]];

// checkIdempotent function call.
if (checkIdempotent(mat))
    console.log("Idempotent Matrix");
else
    console.log("Not Idempotent Matrix.");

// This code is contributed by noob2000.