Rounding errors

[j-faria]

As suggested by Chris Boon & Adam Hill

rounding errors and numerical inaccuracies sometimes mean that the values of CCh and SSh may be computationally equivalent to zero but may not exactly be zero.This can lead to K being positive and the code raising an error. In order to account for these numerical inaccuracies, we have added a catch clause in the code such that if these values fall below a defined threshold (1e-10 is the value I have been using arbitrarily) then it sets CCh and SSh to be exactly zero.

if (CCh < 1e-10):
    CCh = 0
elif (SSh < 1e-10):
    SSh = 0

[j-faria]

I would propose a solution with sys.float.min instead of the arbitrary 1e-10.