not part of the
`StateSpace` system representation (such as `zeros` or `poles`) is very
inefficient and may lead to numerical inaccuracies.  It is better to
convert to the specific system representation first. For example, call
``sys = sys.to_zpk()`` before accessing/changing the zeros, poles or gain.

Examples
--------
>>> import numpy as np
>>> from scipy import signal

>>> a = np.array([[0, 1], [0, 0]])
>>> b = np.array([[0], [1]])
>>> c = np.array([[1, 0]])
>>> d = np.array([[0]])

>>> sys = signal.StateSpace(a, b, c, d)
>>> print(sys)
StateSpaceContinuous(
array([[0, 1],
       [0, 0]]),
array([[0],
       [1]]),
array([[1, 0]]),
array([[0]]),
dt: None
)

Nc