Re: Question about ColorFunction

*To*: mathgroup at smc.vnet.net*Subject*: [mg126604] Re: Question about ColorFunction*From*: Chris Degnen <degnen at cwgsy.net>*Date*: Thu, 24 May 2012 03:30:38 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <jpi3me$4sm$1@smc.vnet.net>

On Wednesday, May 23, 2012 8:30:22 AM UTC+1, Jee Lou wrote: > Anyone explain to me how ColorFunction works? Why Plot3D[Sin[x + y], {x, 0, 3}, {y, 0, 3}, ColorFunction -> (Hue[Sin[#1 + #2]] &)] and Plot3D[Sin[x + y], {x, 0, 3}, {y, 0, 3}, ColorFunction -> (Hue[#3] &)] return different color distributions? The explanation is alluded to in the 'MORE INFORMATION' section of the Help on ColorFunction, at: http://reference.wolfram.com/mathematica/ref/ColorFunction.html I.e. ColorFunction->"name" is equivalent to ColorFunction->(ColorData["name"][#i]&) where the slot used is as follows: Plot, ListPlot, etc.: #2 (y); ArrayPlot, ReliefPlot: #1 (a); ContourPlot, DensityPlot, etc.: #1 (f); ContourPlot3D, etc.: #4 (f); Plot3D, etc.: #3 (z). So in your example: Plot3D[Sin[x + y], {x, 0, 3}, {y, 0, 3}, ColorFunction -> (Hue[Sin[#1 + #2]] &)] #1 and #2 are the x and y values respectively. You can see the effect if you just use Sin[#1] or Sin[#2]. Using #3 uses the z value.