Re: how to graphically fill the tails of a normal distribution

• To: mathgroup at smc.vnet.net
• Subject: [mg50044] Re: [mg50012] how to graphically fill the tails of a normal distribution
• From: DrBob <drbob at bigfoot.com>
• Date: Thu, 12 Aug 2004 05:44:51 -0400 (EDT)
• References: <200408110953.FAA04135@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```I can't read any of that, but maybe this is close to what you want?

Needs["Graphics`"]
Needs["Statistics`"]
f[x_] := PDF[NormalDistribution[0, 1], x]
DisplayTogether[FilledPlot[f[x], {x, -3, -2}, Fills -> Red], Plot[f[
x], {x, -3, 3}], FilledPlot[f[x], {x, 2, 3}, Fills -> Red]]

Bobby

On Wed, 11 Aug 2004 05:53:11 -0400 (EDT), Todd Allen <genesplicer28 at yahoo.com> wrote:

>
> Hello all,
>      Hope you don't mind a question from a biologist trying to learn Mathematica.  I have been teaching myself the syntax of Mathematica to analyze microarray data (i.e, a technology to simultaneously monitor the expression levels of thousands of genes).  I am interested in producing a plot for a presentation in which the tails of a normal distribution are colored red to illustrate a concept.  I can get the plot to work with a single tail, but I can't get the syntax to work for both tails of the disribution.  Here is my code:
>This works for a single tail, with the following code (necessary packages already loaded):
> ndist=NormalDistribution[0,1]
>
> npdf=PDF[ndist,x]
>
> FilledPlot[{npdf,If[x³2,0,npdf]},{x,-4,4},Fills®RGBColor[1,0,0]]
>
> However when I try the following with the Or operator (at least I think Or operator):
>
> FilledPlot[{npdf,If[x³2.0þx£-2.0,0,npdf]},{x,-4,4},Fills®RGBColor[1,0,0]]
>
> I get a series of error messages:
>
> Plot:plnr:If[x³2.0þx£-2.0,0,npdf] is not a machine-size real number at x=-4
>
> This error repeats itself with different x values and then a normal curve is drawn with neither tail colored in.
>
>
>What am I missing here?
>Any insight is much appreciated, thanks!
> Todd
>
>

--
DrBob at bigfoot.com
www.eclecticdreams.net

```

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