bode
Bode plot
Syntax
bode(sl) bode(sl, fmin, fmax) bode(sl, fmin, fmax, step) bode(sl, frq) bode(frq, db, phi) bode(frq, repf) bode(.., Captions) bode(.., "rad")
Arguments
 sl
A siso or simo linear dynamical system, in state space, transfer function or zpk representations, in continuous or discrete time.
 fmin,fmax
real (frequency bounds (in Hz))
 step
real (logarithmic step.)
 frq
row vector or matrix (frequencies (in Hz) ) (one row for each SISO subsystem).
 db
row vector or matrix ( magnitudes (in Db)). (one row for each SISO subsystem).
 phi
row vector or matrix ( phases (in degree)) (one row for each SISO subsystem).
 repf
row vector or matrix of complex numbers (complex frequency response).
 Captions
vector of character strings (captions).
 "rad"
as last optional argument: displays the Bode plot versus Angular frequencies in rad/s, instead of versus frequencies in Hz.
Description
Bode plot, i.e magnitude and phase of the frequency
response of the linear dynamical system sl
.
sl
can be a continuoustime or
discretetime SIMO system given by its state space,
rational transfer function (see syslin) or zpk representation. In case of
multioutput the outputs are plotted with different
colors.
The frequencies are given by the bounds fmin,fmax
(in Hz) or by a rowvector (or a matrix for multioutput)
frq
.
step
is the ( logarithmic ) discretization step.
(see calfrq
for the choice of default value).
db,phi
are the matrices of modulus (in Db) and
phases (in degrees). (One row for each response).
repf
matrix of complex numbers. One row for each
response.
Default values for fmin
and
fmax
are 1.d3
,
1.d+3
if sl
is continuoustime or
1.d3
, 0.5
/sl.dt (nyquist frequency)
if sl
is discretetime. Automatic discretization of
frequencies is made by calfrq
.
The datatips tool may be used to display data along the phase and modulus curves.
Examples
s = poly(0, 's'); h = syslin('c', (s^2+2*0.9*10*s+100)/(s^2+2*0.3*10.1*s+102.01)); clf(); bode(h, 0.01, 100);
See also
 bode_asymp — Bode plot asymptote
 black — BlackNichols diagram of a linear dynamical system
 nyquist — nyquist plot
 gainplot — magnitude plot
 repfreq — frequency response
 g_margin — gain margin and associated crossover frequency
 p_margin — phase margin and associated crossover frequency
 calfrq — frequency response discretization
 phasemag — phase and magnitude computation
 datatips — Tool for placing and editing tips along the plotted curves
History
Version  Description 
5.5.0 

6.0  handling zpk representation 
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