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Mathematica plotting

  1. Feb 11, 2010 #1
    Hi!

    I am plotting the following in Mathematica 7.

    Code (Text):


    RegionPlot3D[(x^2 + y^2 + z^2 <= 1) && (x < 0 || y > 0 ||
        z < 0), {x, -1, 1}, {y, -1, 1}, {z, -1, 1},
     ColorFunction ->
      Function[{x, y, z}, ColorData["TemperatureMap"][x^2 + y^2 + z^2]],
     PlotPoints -> 50, Mesh -> False,
     Lighting -> {{"Directional",
        RGBColor[1, 1, 1], {{-1, 1, -1}, {0, 0, 0}}}},
     AxesLabel -> {X, Y, Z}, {ViewPoint -> {2, -0.5, 0.5}}]

     
    I need the plot to look such that the color on the cut out surface of the sphere should be a gradient in a radial fashion. Assume that there is a point heat source at the center of the sphere and colors represent the temperature profile within the sphere. Any ideas?

    Thanks in advance,
    - N
     
  2. jcsd
  3. Feb 11, 2010 #2

    Dale

    Staff: Mentor

    Add the option ColorFunctionScaling -> False

    I don't know why, but it seems that the scaling is the problem.
     
  4. Feb 11, 2010 #3
    Thanks a lot Dale. I had been struggling with it since a week. Now does anyone have idea as to why. Is this behavior a feature or a bug?

    - N
     
  5. Feb 11, 2010 #4
    Well this seems to be the feature, as the help specifies,

    Parameters to ColorFunction are normally scaled to be between 0 and 1:
    __________________________(by default)_________________________

    So, the parameters are scaled, not the results.

    - N
     
  6. Feb 11, 2010 #5

    Dale

    Staff: Mentor

    That explains it. So it takes x which ranges from -1 to 1 and rescales it to range from 0 to 1, similarly with y and z. Then when you calculate the norm you essentially get a scaled distance from the point (-1,-1,-1)
     
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