freqsepOptions

Options for slow-fast decomposition

Syntax

opt = freqsepOptions

opt = freqsepOptions(Name,Value)

Description

opt= freqsepOptionsreturns the default options forfreqsep.

opt= freqsepOptions(Name,Value)returns an options set with the options specified by one or moreName,Valuepair arguments.

Examples

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Separate Nearby Modes by Adjusting Tolerance

Open Live Script

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 tos= -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 forfreqsepto separate. Increase the relative tolerance to allow the separation.

选择= freqsepOptions('SepTol',5e10); [Gs,Gf] = freqsep(G,2,options);

Nowfreqsepsuccessfully 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

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Name-Value Arguments

Specify optional pairs of arguments asName1=Value1,...,NameN=ValueN, whereNameis the argument name andValueis the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and encloseNamein quotes.

Example:'SepTol',5

`SepTol`—Accuracy loss factor
10(default) |nonnegative scalar

Accuracy loss factor for slow-fast decomposition, specified as a nonnegative scalar value.freqrespensures that the frequency responses of the original system,G, and the sum of the decomposed systemsG1+G2, differ by no more thanSepToltimes the absolute accuracy of the computed value ofG(s). IncreasingSepTolhelps separate modes straddling the slow/fast boundary at the expense of accuracy.