bodemag
Magnitude-only Bode plot of frequency response
Syntax
Description
bodemag
enables you to generate magnitude-only plots to
visualize the magnitude frequency response of a dynamic system.
For a more comprehensive function, see bode
. bode
provides magnitude
and phase information. If you have System Identification™ toolbox,
bode
also returns the computed values, including statistical
estimates.
For more customizable plotting options, see bodeplot
.
bodemag(
creates a Bode
magnitude plot of the frequency response of the dynamic
system model
sys
)sys
. The plot displays the magnitude (in dB) of the system
response as a function of frequency. bodemag
automatically
determines frequencies to plot based on system dynamics.
If sys
is a multi-input, multi-output (MIMO) model, then
bodemag
produces an array of Bode magnitude plots in
which each plot shows the frequency response of one I/O pair.
bodemag(sys1,sys2,...,sysN)
plots the frequency response
of multiple dynamic systems on the same plot. All systems must have the same
number of inputs and outputs.
bodemag(sys1,
specifies a color, line style, and marker for each system in the plot.LineSpec
1,...,sysN,LineSpecN)
bodemag(___,
plots
system responses for frequencies specified by w
)w
.
If
w
is a cell array of the form{wmin,wmax}
, thenbodemag
plots the response at frequencies ranging betweenwmin
andwmax
.If
w
is a vector of frequencies, thenbodemag
plots the response at each specified frequency.
You can use this syntax with any of the input-argument combinations in previous syntaxes.
Examples
Input Arguments
Algorithms
bodemag
computes the frequency response as follows:
Compute the zero-pole-gain (
zpk
) representation of the dynamic system.Evaluate the gain and phase of the frequency response based on the zero, pole, and gain data for each input/output channel of the system.
For continuous-time systems,
bodemag
evaluates the frequency response on the imaginary axis s = jω and considers only positive frequencies.For discrete-time systems,
bodemag
evaluates the frequency response on the unit circle. To facilitate interpretation, the command parameterizes the upper half of the unit circle as:where Ts is the sample time and ωN is the Nyquist frequency. The equivalent continuous-time frequency ω is then used as the x-axis variable. Because is periodic with period 2ωN,
bodemag
plots the response only up to the Nyquist frequency ωN. Ifsys
is a discrete-time model with unspecified sample time,bodemag
uses Ts = 1.
Version History
Introduced in R2012a