Re: How to set y always greater than or equal to x for a function?

*To*: mathgroup at smc.vnet.net*Subject*: [mg46583] Re: How to set y always greater than or equal to x for a function?*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Tue, 24 Feb 2004 21:04:33 -0500 (EST)*Organization*: Universitaet Leipzig*References*: <c1ehpp$kgg$1@smc.vnet.net>*Reply-to*: kuska at informatik.uni-leipzig.de*Sender*: owner-wri-mathgroup at wolfram.com

Hi, Plot3D[] can only handel rectanglular domains but you can try Plot3D[If[y > x, Sqrt[y - x], 0], {x, -100, 100}, {y, -100, 100}]; or you have to use TriangularSurfacePlot[] Regards Jens Albert Franco wrote: > > I recently purchased Mathematica 5.0, and I am in the process of > learning how to take advantage of it's many features. > > This is an example of one line I would like to calculate in Mathematica: > > Plot3D[Sqrt[y-x],{x,-100,100},{y,-100,100}]; > > How can I best edit this line to make y always greater than or equal to x during > calculation so the program doesn't try to take the square root of a > negative number? > > Any help will be appreciated. > > Albert Franco