freqsepOptions
(Not recommended) Options for slow-fast decomposition
freqsepOptions
is not recommended. Specify the SepTol
option directly as a name-value argument to
freqsep
(since R2023b). For more information on updating your
code, see Version History.
Description
Examples
Separate Nearby Modes by Adjusting Tolerance
Decompose a model into slow and fast components between poles that are closely spaced.
The following system includes a real pole and a complex pair of poles that are all close to s = -2.
G = zpk(-.5,[-1.9999 -2+1e-4i -2-1e-4i],10);
Try to decompose the model about 2 rad/s, so that the slow component contains the real pole and the fast component contains the complex pair.
[Gs,Gf] = freqsep(G,2);
Warning: One or more fast modes could not be separated from the slow modes. To force separation, relax the accuracy constraint by increasing the "SepTol" factor (see "freqsepOptions" for details).
These poles are too close together for freqsep
to
separate. Increase the relative tolerance to allow the separation.
options = freqsepOptions('SepTol',5e10);
[Gs,Gf] = freqsep(G,2,options);
Now freqsep
successfully separates the dynamics.
slowpole = pole(Gs)
slowpole = -1.9999
fastpole = pole(Gf)
fastpole = 2×1 complex
-2.0000 + 0.0001i
-2.0000 - 0.0001i
Input Arguments
st
— Accuracy loss factor
10 (default) | nonnegative scalar
Accuracy loss factor for slow-fast decomposition, specified as a
nonnegative scalar value. freqresp
ensures that the
frequency responses of the original system, G
, and the
sum of the decomposed systems G1+G2
, differ by no more
than SepTol
times the absolute accuracy of the computed
value of G(s)
. Increasing SepTol
helps
separate modes straddling the slow/fast boundary at the expense of
accuracy.
Output Arguments
opt
— Options for freqsep
freqsepOptions
options set
Options for freqsep
, returned as a
freqsepOptions
options set. Use
opt
as the last argument to
freqsep
when computing slow-fast
decomposition.
Version History
Introduced in R2014aR2023b: Not recommended
freqsepOptions
is not recommended. Specify the
SepTol
option directly as a name-value argument to
freqsep
. This table describes the change in the
workflow.
Before R2023b | R2023b |
---|---|
opt = freqsepOptions("SepTol",5e10);
[Gs,Gf] = freqsep(G,2,opt); |
[Gs,Gf] = freqsep(G,2,SepTol=5e10); |
See Also
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