`scipy.signal._ltisys:TransferFunctionDiscrete`

source: /scipy/signal/_ltisys.py :818

Signature

class TransferFunctionDiscrete ( * system , ** kwargs )

Summary

Discrete-time Linear Time Invariant system in transfer function form.

Extended Summary

Represents the system as the transfer function $H (z) = \sum_{i = 0}^{N} b [N - i] z^{i} / \sum_{j = 0}^{M} a [M - j] z^{j}$ , where $b$ are elements of the numerator num, $a$ are elements of the denominator den, and N == len(b) - 1, M == len(a) - 1. Discrete-time TransferFunction systems inherit additional functionality from the dlti class.

Parameters

*system: arguments

The TransferFunction class can be instantiated with 1 or 2 arguments. The following gives the number of input arguments and their interpretation:

1: dlti system: (StateSpace, TransferFunction or ZerosPolesGain)
2: array_like: (numerator, denominator)

dt: float, optional

Sampling time [s] of the discrete-time systems. Defaults to True (unspecified sampling time). Must be specified as a keyword argument, for example, dt=0.1.

Notes

Changing the value of properties that are not part of the TransferFunction system representation (such as the A, B, C, D state-space matrices) is very inefficient and may lead to numerical inaccuracies.

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

Examples

Construct the transfer function :math:`H(z) = \frac{z^2 + 3z + 3}{z^2 + 2z + 1}` with a sampling time of 0.5 seconds:

from scipy import signal

✓

num = [1, 3, 3]
den = [1, 2, 1]

✓

signal.TransferFunction(num, den, dt=0.5)

✗

Aliases

scipy.signal._ltisys.TransferFunctionDiscrete