`scipy.signal._ltisys:lti`

source: /scipy/signal/_ltisys.py:136

Signature

class lti(*system)

Members

Summary

Continuous-time linear time invariant system base class.

Parameters

*system : arguments

The lti class can be instantiated with either 2, 3 or 4 arguments. The following gives the number of arguments and the corresponding continuous-time subclass that is created:

2: TransferFunction: (numerator, denominator)
3: ZerosPolesGain: (zeros, poles, gain)
4: StateSpace: (A, B, C, D)

Each argument can be an array or a sequence.

Notes

lti instances do not exist directly. Instead, lti creates an instance of one of its subclasses: StateSpace, TransferFunction or ZerosPolesGain.

If (numerator, denominator) is passed in for *system, coefficients for both the numerator and denominator should be specified in descending exponent order (e.g., s^2 + 3s + 5 would be represented as [1, 3, 5]).

Changing the value of properties that are not directly part of the current system representation (such as the zeros of a StateSpace system) 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

from scipy import signal

✓

signal.lti(1, 2, 3, 4)

✓

StateSpaceContinuous(
array([[1.]]),
array([[2.]]),
array([[3.]]),
array([[4.]]),
dt: None
)

Construct the transfer function :math:`H(s) = \frac{5(s - 1)(s - 2)}{(s - 3)(s - 4)}`:

signal.lti([1, 2], [3, 4], 5)

✓

ZerosPolesGainContinuous(
array([1, 2]),
array([3, 4]),
5,
dt: None
)

Construct the transfer function :math:`H(s) = \frac{3s + 4}{1s + 2}`:

signal.lti([3, 4], [1, 2])

✓

TransferFunctionContinuous(
array([3., 4.]),
array([1., 2.]),
dt: None
)

Aliases

scipy.signal.lti