Idempotent Matrix Check

Problem

Return True if A*A equals A entrywise within a tolerance of 1e-9 (A is idempotent). Otherwise return False.

Projection matrices are the most common idempotent matrices.

Hint

Apply A twice and compare with A; the identity matrix is also idempotent.

case 1

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

expected: true

case 2

in: [[[0.5,0.5],[0.5,0.5]]]

expected: true

case 3

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

expected: false

case 4

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

expected: true

Starter codePython

def is_idempotent(A):
    # Your code here
    pass

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