       Re: NDSolve and Parametric Plot

• To: mathgroup at smc.vnet.net
• Subject: [mg85460] Re: NDSolve and Parametric Plot
• From: janos <janostothmeister at gmail.com>
• Date: Mon, 11 Feb 2008 06:11:10 -0500 (EST)
• References: <fomjh1\$hmn\$1@smc.vnet.net>

```On febr. 10, 11:26, Alex Cloninger <aclonin... at wustl.edu> wrote:
> So I'm trying to run a simple program that will solve this series of diffe=
rential 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*=F0}]
>
> repart[t_] := Re[x[t] /. solution]
> impart[t_] := Im[x[t] /. solution]
>
> ParametricPlot[{repart[t], impart[t]}, {t, 0, 2=F0}, 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 o=
f real numbers at t=2.617993877991494`*^-7
>

Try
ParametricPlot[
Evaluate[{repart[t], impart[t]} /. solution], {t, 0, 2 \[Pi]}]

Hope, it helps,

Janos

```

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