*To*: mathgroup@smc.vnet.net*Subject*: [mg10789] Re: ColorFunction and/or ColorOutput - mkdk*From*: Paul Abbott <paul@physics.uwa.edu.au>*Date*: Thu, 5 Feb 1998 00:58:33 -0500*Organization*: University of Western Australia*References*: <6b3one$rpi@smc.vnet.net>

decker, mark a wrote: > I would also like to clean up all the errors I am generating, by either > defining my function in a different way OR turning off a few of the > error codes. I realize there are undefined regions in the plot. > > Here it is. It was simple enough I didn't even define functions. > > cond = {alpha -> Pi/6, lambda -> 2.15, Ei -> Ep - Es} > > R = lambda Ei Sqrt[ 1 - (Ep/Ei) Sin[alpha]^2 ] > > DensityPlot[R /. cond, {Ep, 0, 6}, {Es,0,4.5}, Mesh->False, > PlotRange->{0,1}, PlotPoints->100 ] > > What I would like to do is the following: > > R<0 be black > > R=0 some bright color. > > 0<R<1 be shaded where R~0 is dark and R~1 is light. > > R>1 be white > > R undefined be some other color. How about color[x_]:= Which[x < 0, GrayLevel[1],x == 5, Hue[1],0<x<1, Hue[x], True, GrayLevel[0]] Off[Power::infy, DensityPlot::plnr, Infinity::indet, DensityGraphics::zval] DensityPlot[Evaluate[R /. cond], {Ep, 0, 6}, {Es,0,4.5}, Mesh->False, PlotPoints->100, ColorFunction->color] You can avoid some of the problems you're encountering by introducing a function, f, like f[Ep_, Es_, alpha_, lambda_] = lambda Ei Sqrt[1 - Ep/Ei Sin[alpha]^2] /. Ei -> Ep - Es When Ep==Es there is a problem. Taking a Limit avoids this: f[Ep_, Ep_, alpha_, lambda_] = Limit[f[Ep, Es, alpha, lambda], Ep -> Es] DensityPlot[f[Ep, Es, Pi/6, 2.15], {Ep, 0, 6}, {Es, 0, 4.5}, Mesh -> False, PlotPoints->100, ColorFunction->color]; Cheers, Paul ____________________________________________________________________ Paul Abbott Phone: +61-8-9380-2734 Department of Physics Fax: +61-8-9380-1014 The University of Western Australia Nedlands WA 6907 mailto:paul@physics.uwa.edu.au AUSTRALIA http://www.pd.uwa.edu.au/~paul God IS a weakly left-handed dice player ____________________________________________________________________