Problem with Manipulate and OutputSystems

*To*: mathgroup at smc.vnet.net*Subject*: [mg128446] Problem with Manipulate and OutputSystems*From*: "Eduardo M. A. M. Mendes" <emammendes at gmail.com>*Date*: Sat, 20 Oct 2012 00:32:45 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net

Dear All I am trying to build an example of third order system with Manipulate. Here are the commands order2withzero[=CE=B6_, =CF=89_, =CE=B3_] := TransferFunctionModel[=CF=89^2/((s^2 + 2 =CE=B6 =CF=89 s + =CF=89^2)*(=CE=B3*s + 1)), s]; Manipulate[{sys = order2withzero[1/5, 5, =CE=B3], sys2 = order2withzero[1/5, 5, 0], Plot[{OutputResponse[sys, UnitStep[t], t], OutputResponse[sys2, UnitStep[t], t]} // Evaluate, {t, 0, 5 + UnitStep[4*=CE=B3 - 5]*4*=CE=B3}, PlotRange -> All]}, Style["Second Order System with an extra pole" , Bold], {=CE=B3, 0.01, 3, Appearance -> "Labeled"}] Problems: a) After shift-enter Mathematica shows me a response of unstable system but the defined systems is always stable. How come? Have I done something wrong? b) For some values of gamma, Mathematica shows an incomplete plot of one the responses. Why? Many many thanks Ed