Re: NDSolve and Parametric Plot

*To*: mathgroup at smc.vnet.net*Subject*: [mg85468] Re: NDSolve and Parametric Plot*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Mon, 11 Feb 2008 06:15:27 -0500 (EST)*References*: <fomjh1$hmn$1@smc.vnet.net>

Hi, solution = NDSolve[{x'[t] == 2 p[t], x[0] == 2, p'[t] == -2 x[t], p[0] == Sqrt[-3]}, {x[t], p[t]}, {t, 0, 2*Pi}]; repart[tau_] := (Re[x[t] /. solution[[1]]] ) /. t -> tau impart[tau_] := (Im[x[t] /. solution[[1]]] ) /. t -> tau ParametricPlot[{repart[t], impart[t]}, {t, 0, 2 Pi}, PlotRange -> {{-2, 2}, {-2, 2}}] may help. Regards Jens Alex Cloninger wrote: > So I'm trying to run a simple program that will solve this series of di= fferential equations and plot the the x[t] function in the complex plane.= Here's my code. > > solution = NDSolve[{x'[t] == 2p[t], x[0] == 2, p'[t] == -= 2x[t], p[0] == Sqrt[-3]}, {x, p}, {t, 0, 2*=CF=80}] > > repart[t_] := Re[x[t] /. solution] > impart[t_] := Im[x[t] /. solution] > > ParametricPlot[{repart[t], impart[t]}, {t, 0, 2=CF=80}, PlotRange -> {{= -2, 2}, {-2,2}}] > > For some reason, when I go to plot the curve, I get an error saying > ParametricPlot::pptr: {repart[t], impart[t]} does not evaluate to a pai= r of real numbers at t=2.617993877991494`*^-7 > > What's going on? Could someone please help me with this? >