       RE: Incorrect plotting of Lissajous-figures

• To: mathgroup at smc.vnet.net
• Subject: [mg25908] RE: [mg25890] Incorrect plotting of Lissajous-figures
• From: "David Park" <djmp at earthlink.net>
• Date: Tue, 7 Nov 2000 23:04:56 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

```Rene,

You probably want this:

ParametricPlot[{Cos[500*t], Cos[500*t + Pi/4]}, {t, 0, 2*Pi/500}]

The reason the ellipse is being filled is that 25 plot points are being used
and lines are being drawn bewteen ajacent points. But with so few points,
and with the entire range wrapping around the ellipse many times, the points
are almost randomly placed and the lines go across the ellipse. If you must
use the extended range, increase the plot points.

ParametricPlot[{Cos[500*t], Cos[500*t + Pi/4]}, {t, 0, 2*Pi},
PlotPoints -> 500]

David Park

> -----Original Message-----
> From: Rene Meyer [mailto:rene.meyer at s2000.tu-chemnitz.de]
To: mathgroup at smc.vnet.net
> Hello,
>
> while using Mathematica 4.0.2.0 to plot a Lissajous-figure with
>
> ParametricPlot[{Cos[500t], Cos[500t + Pi/4]}, {t, 0, 2Pi}]
>
> I found that with growing coefficients of t the figure (which should
> be a ellipse with an angle of 45 degrees between its longer main axis and
> the x axis) have the effect of filling up the whole ellipse with
> points. Is this an effect of rounding errors or is this a bug in
> mathematica?
>
> --
> Rene Meyer
> Student of Physics - Chemnitz University of Technology

```

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