Re: Piecewise ColorFunction

*To*: mathgroup at smc.vnet.net*Subject*: [mg125657] Re: Piecewise ColorFunction*From*: "djmpark" <djmpark at comcast.net>*Date*: Mon, 26 Mar 2012 01:46:39 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <22324383.161322.1332653209094.JavaMail.root@m06>

Two problems: the symbol f is not a Function, and ColorFunctionScaling-> False is needed. ClearAll[f]; f[x_, y_] := Piecewise[{{Green, y < 0}, {Red, y >= 0}}] Plot[Sin[x], {x, 0, 4 Pi}, PlotStyle -> Thick, ColorFunctionScaling -> False, ColorFunction -> (f[#1, #2] &)] Or define something that is a Function. ClearAll[g]; g := Function[{x, y}, Piecewise[{{Green, y < 0}, {Red, y >= 0}}]] Plot[Sin[x], {x, 0, 4 Pi}, PlotStyle -> Thick, ColorFunctionScaling -> False, ColorFunction -> g ] Otherwise, your use of Piecewise is a neat way to color! David Park djmpark at comcast.net http://home.comcast.net/~djmpark/index.html From: Hugh Goyder [mailto:h.g.d.goyder at cranfield.ac.uk] The first example below works to give a plot style with colours that vary with y-values. I then try to define a Piecewise function for the colour and this does not work. Am I doing something wrong? Thanks for any assistance. Plot[Sin[x], {x, 0, 4 Pi}, PlotStyle -> Thick, ColorFunction -> Function[{x, y}, ColorData["NeonColors"][y]]] ClearAll[f]; f[x_, y_] := Piecewise[{{Green, y < 0}, {Red, y >= 0}}] Plot[Sin[x], {x, 0, 4 Pi}, PlotStyle -> Thick, ColorFunction -> f]