Module « scipy.signal »

Fonction freqresp - module scipy.signal

Signature de la fonction freqresp

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

Description

freqresp.__doc__

Calculate the frequency response of a continuous-time system.

    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

    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]``).

    Examples
    --------
    Generating the Nyquist plot of a transfer function

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

    Construct the transfer function :math:`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()