freson

Arguments

h

A siso linear dynamical system, in state space, transfer function or zpk representations.

fr

vector of peak frequencies in Hz

Description

returns the vector frequencies at which the response amplitude of a siso dynamical system is a relative maximum also called resonance frequencies.

Examples

Continuous time system

h = syslin('c',-1+%s,(3+2*%s+%s^2)*(50+0.1*%s+%s^2));
fr = freson(h)
clf
bode(h);
fig=gcf();sca(fig.children(2));
[phi,db] = phasemag(repfreq(h,fr));
plot(fr,db(:),'+r')

Discrete time system

h = syslin('c',-1+%s,(3+2*%s+%s^2)*(50+0.1*%s+%s^2));
hd = dscr(h, 0.05);
fr = freson(hd)
clf
bode(hd);
fig=gcf();sca(fig.children(2));
[phi,db] = phasemag(repfreq(hd,fr));
plot(fr,db(:),'+r');

See also

• frep2tf — transfer function realization from frequency response
• zgrid — zgrid plot
• h_norm — H-infinity norm

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