PSD Kernel Check 2x2

Problem

Return True if the 2x2 matrix K is a valid positive semidefinite kernel matrix: symmetric within 1e-9, trace >= 0, and determinant >= -1e-9.

Otherwise return False.

Hint

For a 2x2 symmetric matrix, PSD is equivalent to non-negative trace and determinant.

case 1

in: [[[1,0.5],[0.5,1]]]

expected: true

case 2

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

expected: false

case 3

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

expected: true

case 4

in: [[[1,2],[3,1]]]

expected: false

Starter codePython

def is_psd_kernel_2x2(K):
    # Your code here
    pass

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