RE: Re: Plotting bounded domains

*To*: mathgroup at smc.vnet.net*Subject*: [mg23230] RE: [mg23211] Re: [mg23110] Plotting bounded domains*From*: "David Park" <djmp at earthlink.net>*Date*: Tue, 25 Apr 2000 01:40:33 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Gurzen and everybody, I made an earlier reply to this question where I assumed that the original poster wanted a contour plot of the function. However, Bob Hanlon assumed a Plot3D type solution. The DrawingCube package also allows that type of plot. It plots only in the desired region and it does not produce a jagged edge along one side as the Hanlon solution does. Here is the code: Needs["Graphics`DrawingCube`"] IteratorSubstitution[x y, {y, 0, x}] {w*x^2, {w, 0, 1}} Show[Graphics3D[ {Draw3D[w x^2, {x, 0, 2}, {w, 0, 1}] /. DrawingTransform3D[Function[{x, w, z}, x], Function[{x, w, z}, x w], Function[{x, w, z}, z]]}], AspectRatio -> Automatic, PlotRange -> {{0, 2}, {0, 2}, {0, 4}}]; The Drawing packages can be downloaded from my web site below. David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ > From: Gurzen Nezrug [mailto:gurzen at has.no.e.mail] To: mathgroup at smc.vnet.net > Hello bob and group, > > I would like to second the question and object the answer. > Bob Hanlon nice trick result with a function which is f(x,y)=x*y in the > wanted region and f(x,y)=0 outside. But what I want, and possibly what > jgregory wants (If I'm allowed to guess) is to see only the inner part and > nothing on the outer part (i.e. clear background). To justify my question, > suppose that f(x,y) is now 0 for x<1, how can we tell between the > real 0 and > the "outside the region" 0 ?!? > Is there a way to get such plot other then parametrizing the > area "by hand" > (which might not be simple) and using ParametricPlot3D? > I would like to add, knowing software such as MATLAB (I hope it is not > forbidden to mention this name here) assigning a value of NaN to > a function > or a matrix (stands for "Not a Number") means that this point will simply > not be shown in graphics plot. Is there a way to achieve the same within > mathematica? > > Thank you all, > > BobHanlon at aol.com wrote in message <8dnvsh$hua at smc.vnet.net>... > >f[x_, y_] := x*y; > > > >region[x_, y_] := > > (UnitStep[x] - UnitStep[x - 2.])*(UnitStep[y] - UnitStep[y - x]); > > > >Plot3D[f[x, y]*region[x, y], {x, -0.5, 2.5}, {y, -0.5, 3.5}, > > PlotPoints -> 35, AxesLabel -> {"x", "y", "z"}, > > ViewPoint -> {1.300, -2.400, 2.000}]; > > > >Bob Hanlon > > > >In a message dated 4/19/2000 2:44:33 AM, jgregory at ismi.net writes: > > > >> In Mathematica, how does one plot a bounded and closed domain in R^2 > >>that includes variables? For example let R be y=x; x=2; y = 0; for the > >>function, f(x,y) = x*y. > >> > >