cupyx.scipy.signal.TransferFunction#

class cupyx.scipy.signal.TransferFunction(*system, **kwargs)[source]#

Linear Time Invariant system class in transfer function form.

Represents the system as the continuous-time transfer function \(H(s)=\sum_{i=0}^N b[N-i] s^i / \sum_{j=0}^M a[M-j] s^j\) or the discrete-time 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. TransferFunction systems inherit additional functionality from the lti, respectively the dlti classes, depending on which system representation is used.

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: lti or dlti system: (StateSpace, TransferFunction or ZerosPolesGain)
- 2: array_like: (numerator, denominator)
dt (float, optional) – Sampling time [s] of the discrete-time systems. Defaults to None (continuous-time). Must be specified as a keyword argument, for example, dt=0.1.

See also

scipy.signal.TransferFunction, ZerosPolesGain, StateSpace, lti, dlti, tf2ss, tf2zpk, tf2sos

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. It is better to convert to the specific system representation first. For example, call sys = sys.to_ss() before accessing/changing the A, B, C, D system matrices.

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 or z^2 + 3z + 5 would be represented as [1, 3, 5])

Methods

to_ss()[source]#

Convert system representation to StateSpace.

Returns:: sys – State space model of the current system
Return type:: instance of StateSpace

to_tf()[source]#

Return a copy of the current TransferFunction system.

Returns:: sys – The current system (copy)
Return type:: instance of TransferFunction

to_zpk()[source]#

Convert system representation to ZerosPolesGain.

Returns:: sys – Zeros, poles, gain representation of the current system
Return type:: instance of ZerosPolesGain

__eq__(value, /)#: Return self==value.

__ne__(value, /)#: Return self!=value.

__lt__(value, /)#: Return self<value.

__le__(value, /)#: Return self<=value.

__gt__(value, /)#: Return self>value.

__ge__(value, /)#: Return self>=value.

Attributes

den#: Denominator of the TransferFunction system.

dt#: Return the sampling time of the system, None for lti systems.

num#: Numerator of the TransferFunction system.

poles#: Poles of the system.

zeros#: Zeros of the system.