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I am trying to plot step response of a system with an approximated delay. This code

a = 2; pa = PadeApproximant[Exp[-s], {s, 0, {3, 3}}]; sys = TransferFunctionModel[pa/(s^2 + s/a + 1), s]; out = OutputResponse[sys, UnitStep[t], {t, 0, 20}]; Plot[out, {t, 0, 20}, PlotRange -> All]

produces discontinuous plot below

disc

If we change the value of a to be positive number other than 2, then the discontinuities disappear. How to remove these discontinuities for $a=2$? I am using Wolfram 14.2.

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    $\begingroup$ Re@out seems work. Or ReImPlot. $\endgroup$ Commented Feb 5 at 12:19
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    $\begingroup$ The discontinuities disappear when you write "a=2." instead of "a=2". $\endgroup$ Commented Feb 5 at 13:12

1 Answer 1

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Add Chop to clean it a little. Since your OutputResponse is numerical and not analytical (because you used {t, 0, 20} and not just t) the result when looking at it had lots of numerical artifacts.

a = 2; pa = PadeApproximant[Exp[-s], {s, 0, {3, 3}}]; sys = TransferFunctionModel[pa/(s^2 + s/a + 1), s]; out = OutputResponse[sys, UnitStep[t], {t, 0, 20}]; Plot[Chop@out, {t, 0, 20}, PlotRange -> All]

enter image description here

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