Download - Wolfram Research

84 2. Tutorial
In[3]:= BodePlot[H1[I w], {w, 0.001, 1000.}]
Magnitude (dB)
60
40
20
0
-20
-40
-60
1.0E-3 1.0E-2 1.0E-1 1.0E0 1.0E1 1.0E2 1.0E3
Frequency
Phase (deg)
0
-25
-50
-75
-100
-125
-150
-175
1.0E-3 1.0E-2 1.0E-1 1.0E0 1.0E1 1.0E2 1.0E3
Frequency
Out[3]= Graphics
BodePlot Options
The output generated by BodePlot is influenced by a number of options listed in
Options[BodePlot], many of which are inherited from Options[LogLinearListPlot] from Mathematica’s
standard package Graphics‘Graphics‘. Here, we will discuss only some of those options
which pertain exclusively to BodePlot or which must be used with a different syntax as compared
to LogLinearListPlot. The relevant options and their default settings are listed below. Defaults
are listed first, followed by the possible alternatives printed in slanted typewriter font.
MagnitudeDisplay −> Decibels | AbsoluteValues | Linear
PhaseDisplay −> Degrees | Radians
PlotRange −> {Automatic, Automatic}
The option MagnitudeDisplay controls the display of the magnitude values. When set to
AbsoluteValues, magnitude values are not converted to decibels. Instead the absolute numerical
values are displayed on a logarithmic scale. When MagnitudeDisplay is set to Linear, magnitude
values are displayed on a linear scale. In a strict sense, the latter does no longer constitute a true
Bode plot, but there exist a few applications where linear magnitude scaling is useful.
With the value of the option PhaseDisplay we can choose whether phase values are shown as
degrees or as radians.
The meaning of the PlotRange option is slightly different for BodePlot than for other Mathematica
plotting commands. Here, the value of PlotRange must be a list of two elements, {range m
, range p
},
specifying the plot ranges of the y-axes of the magnitude and the phase chart respectively. PlotRange
has no effect on the ranges of the x-axes as these are determined by the given frequency range. The
format for both y-ranges is the usual one as documented in the Mathematica manual, so any of the
forms below are valid syntax: