Re: OutputResponse gives funny results

*To*: mathgroup at smc.vnet.net*Subject*: [mg128512] Re: OutputResponse gives funny results*From*: richard i pelletier <bitbucket at comcast.net>*Date*: Thu, 25 Oct 2012 23:35:47 -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*References*: <k62nr9$cg9$1@smc.vnet.net>

In article <k62nr9$cg9$1 at smc.vnet.net>, "Eduardo M. A. M.Mendes" <emammendes at gmail.com> wrote: > Tcl[p_,Kp_,Kd_,Ki_]=TransferFunctionModel[(Ki+Kp s+Kd s^2)/(Ki+Kp s+Kd > s^2+p^2 s^2+2 p s^3+s^4),s] > > fcl[t_,p_,Kp_,Kd_,Ki_]=Abs[OutputResponse[Tcl[p,Kp,Kd,Ki],UnitStep[t],t]]; > > Manipulate[{N[TransferFunctionPoles[Tcl[p,6,4,1]],2],Plot[fcl[t,p,6,4,1],{t, > 0,Ts},PlotRange->All,AxesLabel->{t,x[t]},PlotStyle->Thickness[0.01],GridLine > s->Automatic]},Style["Example 4.4 - Dorf - 12^th Edition - R(s) = 10/s, D(s) > = > 0",Bold],{{p,2},0,100,Appearance->"Labeled"},{{Ts,20},0.1,100,Appearance->"L > abeled"}] > > Even though the poles are on the left side (stable system), OutResponse > gives huge numbers (instability) when the slider for the variable Ts is > moved to higher values. More than, it is seems that this simple code makes > Mathematica ever so slow. > as I just posted in response to your comment on my blog, the problem is with Output Response i don't know why... Simplify didn't seem to help but if i compute and plot the inverse Laplace transform (for a unit step input), everything looks fine. rip -- email address is r i p 1 AT c o m c a s t DOT n e t