Re: ContourPlot problem

• To: mathgroup at smc.vnet.net
• Subject: [mg15507] Re: ContourPlot problem
• From: "Allan Hayes" <hay at haystack.demon.co.uk>
• Date: Mon, 18 Jan 1999 23:47:11 -0500
• References: <77uukf\$kb8@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Pedro A Santos wrote in message <77uukf\$kb8 at smc.vnet.net>...

>When I give the command
>
>ContourPlot[(1-Exp[-1/((x)^2+(y)^2)/10]),{x,-1.0,1.0},{y,-1.0,1.0},
>  PlotPoints ->{50,50},
>  Contours -> {.1,.2,.3,.4,.5,.6,.7,.8,.9,.99, .99999999},
>
>I get what would be to expect, i.e. all the contours. But if I change
>slightly the domain,
>say  "{x,-1.1,1.1},{y,-1.1,1.1}", the majority of the contours
>disappear. And they do not appear even if I increase PlotPoints to 200
>or more.
>
>Does anybody know the reason of this strange behaviour? And how to avoid
>it?

Pedro,

This is caused by Mathematica showing only what it thinks is interesting
With "{x,-1.1,1.1},{y,-1.1,1.1}" the same data is available as in the
first case but not all of it is displayed.

ContourPlot[(1-Exp[-1/((x)^2+(y)^2)/10]),{x,-1.1,1.1},{y,-1.1,1.1},
PlotPoints ->{50,50},
->False];

We can correct this retrospectively using Show

Show[%, PlotRange->All];

or we can use the option in ContourPlot:

ContourPlot[(1-Exp[-1/((x)^2+(y)^2)/10]),{x,-1.1,1.1},{y,-1.1,1.1},
PlotPoints ->{50,50},
->False,
PlotRange -> All];

If we don't want to see everything we can specify the range of  heights
by PlotRange -> {0,1.2}, for example.

Allan

---------------------
Allan Hayes
Mathematica Training and Consulting
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565

```

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