Diagonal Matrix Check

Problem

Check whether a square matrix is diagonal.

Return True when every off-diagonal entry has absolute value below 1e-9. Diagonal entries themselves can be anything, including zero.

Hint

Only entries where row index differs from column index need checking.

case 1

in: [[[1,0],[0,2]]]

expected: true

case 2

in: [[[1,0],[0,1]]]

expected: true

case 3

in: [[[1,1],[0,1]]]

expected: false

case 4

in: [[[0,0],[0,0]]]

expected: true

case 5

in: [[[1,1e-10,0],[0,2,0],[0,0,3]]]

expected: true

Starter codePython

def diagonal_matrix_check(A):
    # Your code here
    pass

5 test cases · run your code against them in the editor