"Is there a way to keep zeros as zeros? "
Zeros are zeros.
But the data you show are not zero: the trailing digits tell us that those values are not zero. Compare:
V = [0,eps(0),pi,-pi] % zero and not-zero and +pi and -pi
Is the 1st value zero? Yes (note no trailing digits).
Is the 2nd value zero? No (the trailing digits tell us this).
So the answer is very clear, that you need to take into account that those values are not zero.
For example, use a tolerance:
tol = 1e-5;
Z = (V>tol)-(V<-tol)
or use ROUND beforehand:
W = round(V,5) % look, those are *exactly* zero!
Z = (W>0)-(W<0)
