Re: Problem using Evaluate[] inside a Plot command. 5.1

*To*: mathgroup at smc.vnet.net*Subject*: [mg54254] Re: Problem using Evaluate[] inside a Plot command. 5.1*From*: "Carl K. Woll" <carlw at u.washington.edu>*Date*: Mon, 14 Feb 2005 21:50:49 -0500 (EST)*Organization*: University of Washington*References*: <cu78ub$me9$1@smc.vnet.net> <cumor4$3rc$1@smc.vnet.net> <cup5b7$drp$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Nasser, Try putting Evaluate around the entire first argument of Plot, as in Plot[ Evaluate[{t^2, OutputResponse[sys, UnitStep[t], t] }], {t, 0, 3}, PlotRange -> All] Carl Woll "Nasser Abbasi" <nma at 12000.org> wrote in message news:cup5b7$drp$1 at smc.vnet.net... >D Herring wrote: > >> Hi Nasser, >> >> Maybe Evaluate[OutputResponse[sys,UnitStep[t], t]] is returning a value >> which needs to be Evaluate[]d again before it can be plotted? >> >> I've never had your problem (don't even have the control toolbox), but >> maybe >> >> Plot[{t2, Evaluate[Evaluate[OutputResponse[sys,UnitStep[t], t]]]}, >> {t, 0, 3}, PlotRange -> All] >> >> might work? >> >> Your error message, "plot::plnr: .... is not a machine-size real >> number at t=...." usually indicates the need to Evaluate[] one of the >> Plot[] arguments. >> >> Good luck, >> Daniel >> > > Daniel; > > I tried your command above (You had a typo, 't2' should > be 't^2' or just 't'), any way, it does not work either. > > I am sure this is a bug in Mathematica, either the kernel or the > ControlSystems toolbox or the parser. > > It does not make sense for this command to work: > > Plot[ Evaluate[OutputResponse[sys, UnitStep[t], t]] , > {t, 0, 3}, PlotRange -> All] > > But if I now simply combine another function in the plot command, > so to plot 2 functions together, it will now fail: > > Plot[ {t^2, Evaluate[OutputResponse[sys, UnitStep[t], t]] }, > {t, 0, 3}, PlotRange -> All] > "plot::plnr: .... is not a machine-size real > > > Why would the second example above fail but the first not fail? > > btw, the output from the OutputResponse[] is simply a list that > contains a function of t, such as { Exp[t/2] Cos[t] } > > So, nothing too complicated here. > > bye, > Nasser > > > >