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Re: SphericalPlot3D ColorFunction problem

  • To: mathgroup at smc.vnet.net
  • Subject: [mg104678] Re: [mg104653] SphericalPlot3D ColorFunction problem
  • From: Brett Champion <brettc at wolfram.com>
  • Date: Sat, 7 Nov 2009 06:43:54 -0500 (EST)
  • References: <200911061014.FAA07949@smc.vnet.net>

On Nov 6, 2009, at 4:14 AM, Porscha Louise McRobbie wrote:

> Hello,
>
> Can anyone explain why the following simple plot is a single color?
>
> SphericalPlot3D[Abs[Cos[t]], {t, 0, Pi}, {p, -Pi, Pi},
>  ColorFunction -> Function[{t}, Hue[Arg[Cos[t]]/(2. Pi)]],
>  ColorFunctionScaling -> False]
>
> Arg[Cos[t]]/(2. Pi)] should be zero for t<Pi/2, and 0.5 for t>Pi/2, so
> I expect the the upper lobe of the plot to be red (Hue[0]) and the
> lower lobe to be cyan (Hue[0.5]).  Is there something different about
> ColorFunctions in SphericalPlot3D compared with Plot3D?
>
> Any help is greatly appreciated!

You want: ColorFunction -> Function[{x, y, z, t, p, r},  
Hue[Arg[Cos[t]]/(2. Pi)]]

Even though you refer to it as t, the parameter in your function is  
being passed the x values.

Brett Champion
Wolfram Research


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