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freqresp(system, w=None, n=10000)

Notes

If (num, den) 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] ).

Parameters

system : an instance of the `lti` class or a tuple describing the system.

The following gives the number of elements in the tuple and the interpretation:

  • 1 (instance of lti )

  • 2 (num, den)

  • 3 (zeros, poles, gain)

  • 4 (A, B, C, D)

w : array_like, optional

Array of frequencies (in rad/s). Magnitude and phase data is calculated for every value in this array. If not given, a reasonable set will be calculated.

n : int, optional

Number of frequency points to compute if w is not given. The n frequencies are logarithmically spaced in an interval chosen to include the influence of the poles and zeros of the system.

Returns

w : 1D ndarray

Frequency array [rad/s]

H : 1D ndarray

Array of complex magnitude values

Calculate the frequency response of a continuous-time system.

Examples

Generating the Nyquist plot of a transfer function

>>> from scipy import signal
... import matplotlib.pyplot as plt

Construct the transfer function $H(s) = \frac{5}{(s-1)^3}$ :

>>> s1 = signal.ZerosPolesGain([], [1, 1, 1], [5])
>>> w, H = signal.freqresp(s1)
>>> plt.figure()
... plt.plot(H.real, H.imag, "b")
... plt.plot(H.real, -H.imag, "r")
... plt.show()
See :

Back References

The following pages refer to to this document either explicitly or contain code examples using this.

scipy.signal._ltisys.lti.freqresp scipy.signal._ltisys.freqresp

Local connectivity graph

Hover to see nodes names; edges to Self not shown, Caped at 50 nodes.

Using a canvas is more power efficient and can get hundred of nodes ; but does not allow hyperlinks; , arrows or text (beyond on hover)

SVG is more flexible but power hungry; and does not scale well to 50 + nodes.

All aboves nodes referred to, (or are referred from) current nodes; Edges from Self to other have been omitted (or all nodes would be connected to the central node "self" which is not useful). Nodes are colored by the library they belong to, and scaled with the number of references pointing them


GitHub : /scipy/signal/_ltisys.py#2578
type: <class 'function'>
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