I am trying to produce a graph of the linear dynamic system response to a step input.

The code is as follows:

ssm=StateSpaceModel[{

8*x”[t] + 0.1*x'[t] + 0.64*k*(0.64*x[t] – y[t]) == u[t],

25*y”[t] + 0.08*y'[t] + k*(y[t] – 0.64*x[t]) == 0},

{{x'[t],0}, {x[t],0}, {y'[t],0}, {y[t],0}},

{{u[t],0}}, {y'[t]}, t];

klist = {5, 100, 350, 750};

result = Table[OutputResponse[ssm /. k -> i,

100 UnitStep[t], t], {i, klist}];

TableForm[Partition[Table[Plot[result[[i]], {t, 0, 1000},

PlotLabel -> (“k =” <> ToString[klist[[i]]])], {i, 1, 4}], 2]]

For some reason portions of 3 plots are missing, as shown in the figure:

How can I fix that so that plots are displayed in their entirety?

Note: In Mathematica 10.3.1 these very plots were generated in full with no problem. Now, when i upgraded to 10.4 this problem has surfaced.

thank you very much for your help.

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1 Answer

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If you look at the FullForm of your variable result you will see that it contains some small complex numbers. You can remove these by using Plot[Abs[result[[i]]] instead.

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Or just use Chop, i.e., Plot[result[[i]] // Chop, …

– Bob Hanlon

Apr 27 at 4:31