freqresp

Evaluate system response over a grid of frequencies.

Syntax

• [H, wout] = freqresp(sys, w)
• H = freqresp(sys, w)

Input argument

• sys - LTI model
• w - Frequencies: vector

Output argument

• H - Frequency response values
• wout - Output frequencies corresponding to the frequency response: vector.

Description

freqresp computes the frequency response of a dynamic system sys at specified frequencies w.

To acquire magnitude and phase data, along with visual representations of the frequency response, utilize the bode function.

Examples

G = tf(1,[1 1]);
h1 = freqresp(G, 3)

num = [1 2];
den = [1 3 2];
sys = tf(num,den);
w = linspace(0, 100, 60);
[resp,freq] = freqresp(sys, w);

f = figure();
subplot(2, 1, 1);
plot(freq, 20 * log10(abs(squeeze(resp))));
ylabel(_('Amplitude (dB)'));
subplot(2, 1, 2);
plot(freq, angle(squeeze(resp)) * 180/pi);
ylabel(_('Phase (degrees)'));
xlabel(_('Frequency (Hz)'));

See also

bode, evalfr.

History

Author

Allan CORNET