*To*: mathgroup@smc.vnet.net*Subject*: [mg10335] RE: [mg10312] Mathematica Plot [help]*From*: "Richard W. Finley, M. D." <trfin@umsmed.edu>*Date*: Thu, 8 Jan 1998 23:40:57 -0500

Hi One easy way to do it: f[x_,y_] := Sin[x y] /; y <= 1 - x f[x_,y_] := 0 /; y > 1 - x Plot3D[f[x,y],{x,0,1},{y,0,1}] Regards, RF -----Original Message----- From: Wei Xu [SMTP:wxu@cs.utexas.edu] To: mathgroup@smc.vnet.net Sent: Monday, January 05, 1998 9:25 PM To: mathgroup@smc.vnet.net Subject: [mg10312] Mathematica Plot [help] Hi, I'm learning Mathematica. I want to draw a surface, say sin[x,y], defined on a triangular domain, say, x:[0,1], y:[0,1] and x+y <=1. I tried to use the following command: ParametricPlot3D[{fx, fy, fz}, {x,0,1}, {y,0,1-x}] but it is not allowed to use {y,0,1-x}. Anybody can help me out? Thanks, Regards, Wei