Checking 2 Port SMD Device for Passivity

I have seen some simulators have a 'check passivity' function. I'm curious on what the formula/algorithim is to do this myself (e.g. Excel or VBA)?

From what I understand there is an eigen value which needs to be calculated from the S-parameter matrix. That's as much I can figure out.

See GJM1555C1H470FB01 example attached.

Thank you for any insight.