Re: Contour line colors from z coord of a 3D plot

• To: mathgroup at smc.vnet.net
• Subject: [mg117189] Re: Contour line colors from z coord of a 3D plot
• From: "Kevin J. McCann" <Kevin.McCann at umbc.edu>
• Date: Thu, 10 Mar 2011 16:04:45 -0500 (EST)

```If you use a ListPlot3D and ListContourPlot instead, it will get rid of
the annoying and puzzling lack of a plot along the negative real axis.

On 3/10/2011 6:43 AM, Bob Hanlon wrote:
> Module[{f, ch = Purple, cl = Yellow},
>   f[x_, y_] := Log[x + I y];
>   logre = Show[
>     Plot3D[Re[f[x, y]],
>      {x, -2.4, 2.4}, {y, -2, 2},
>      PlotStyle ->  Opacity[0.7],
>      PlotRange ->  {-3, 1.5},
>      ColorFunction ->
>       (Blend[{cl, ch}, #3]&),
>      MeshStyle ->  Darker[Gray]],
>     Graphics3D[
>      ContourPlot[Re[f[x, y]],
>         {x, -2.4, 2.4}, {y, -2, 2},
>         Axes ->  False,
>         Contours ->  Table[z, {z, -1, 1, .25}],
>         ContourStyle ->
>          Table[
>           Blend[{cl, ch}, (z + 1)/2],
>           {z, -1, 1, .25}]][[1]] /.
>       {x_Real, y_Real} ->  {x,
>         y, -3}],
>     ViewPoint ->  {2.2, -4, 1.3},
>     ImageSize ->  400]]
>
>
> Bob Hanlon
>
> ---- recmath<recmath99 at gmail.com>  wrote:
>
> =============
> Hi there,
>
> I'm trying to reproduce this very cool figure:
> http://en.wikipedia.org/wiki/File:NaturalLogarithmRe.png
>
> Problem: I can't get the contour lines color-matched to the 3D
> surface, which is colored according to it's height. My code is below,
> can anyone help?
>
>
> Module[{f}, f[x_, y_] := Log[x + I y];
>
>   logre = Show[Plot3D[Re[f[x, y]], {x, -2.4, 2.4}, {y, -2, 2},
>      PlotStyle ->  Opacity[0.7], Axes ->  True, Boxed ->  True,
>      PlotRange ->  {Automatic, Automatic, {-3, 4}},
>      ColorFunction ->  (Blend[{Yellow, Purple}, #3]&)],
>     Graphics3D[
>      ContourPlot[Re[f[x, y]], {x, -2.4, 2.4}, {y, -2, 2},
>         Axes ->  False, ContourShading ->  None,
>         ContourStyle ->  Purple][[
>        1]] /. {x : _Real, y : _Real} ->  {x, y, -3}],
>     ViewPoint ->  {2.2, -4, 1.3}, ImageSize ->  300
>     ]
>   ]
>
>

```

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