       Re: NDSolve and Parametric Plot

• To: mathgroup at smc.vnet.net
• Subject: [mg85466] Re: NDSolve and Parametric Plot
• From: Peter Breitfeld <phbrf at t-online.de>
• Date: Mon, 11 Feb 2008 06:14:19 -0500 (EST)
• References: <fomjh1\$hmn\$1@smc.vnet.net>

```Alex Cloninger schrieb:
> So I'm trying to run a simple program that will solve this series of differential equations and plot the the x[t] function in the complex plane.  Here's my code.
>
> solution = NDSolve[{x'[t] == 2p[t], x == 2, p'[t] == -2x[t],
p == Sqrt[-3]}, {x, p}, {t, 0, 2*Ï?}]
>
> repart[t_] := Re[x[t] /. solution]
> impart[t_] := Im[x[t] /. solution]
>
> ParametricPlot[{repart[t], impart[t]}, {t, 0, 2Ï?},
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 pair of real numbers at t=2.617993877991494`*^-7
>
>

You should write:
repart:=Re[ x[t]/.solution[] ]
impart:=Im[ x[t]/.solution[] ]

ParametricPlot[{repart,impart},{t,0,2Pi}]

Gruss Peter
--
==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==
Peter Breitfeld, Bad Saulgau, Germany -- http://www.pBreitfeld.de

```

• Prev by Date: Re: NDSolve and Parametric Plot
• Next by Date: Re: more looping trouble
• Previous by thread: Re: NDSolve and Parametric Plot
• Next by thread: Import syntax question