Steady function

[capocchi]

According to the following matrix implemented in a file fn and loaded using readmat function, the steady function randomly return a list of 0. I use python in version 3.7.

R R .5
R N .25
R S .25
N R .5
N N 0
N S .5
S R .25
S N .25
S S .5

Markov matrix

P = pykov.readmat(fn)
Pi = P.steady()
assert(Pi.sum()!=0)

Thanks in advance.