Minimal Polynomial 2x2

Problem

Return the coefficients of the minimal polynomial of a 2x2 matrix A.

If A = lam*I, the minimal polynomial is degree 1 and the coefficients are [1.0, -lam]. Otherwise it equals the characteristic polynomial [1.0, -tr(A), det(A)].

Hint

Scalar matrices are the only 2x2 matrices whose minimal polynomial has degree 1.

Test cases

case 1

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

expected: [1,-2]

case 2

in: [[[2,0],[0,3]]]

expected: [1,-5,6]

case 3

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

expected: [1,-2,1]

case 4

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

expected: [1,0]

Starter codePython

def minimal_polynomial_2x2(A):
    # Your code here
    pass

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