Re: Graphics--If condition in Plot3D?????????

*To*: mathgroup at smc.vnet.net*Subject*: [mg69040] Re: Graphics--If condition in Plot3D?????????*From*: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>*Date*: Sun, 27 Aug 2006 01:24:23 -0400 (EDT)*Organization*: The Open University, Milton Keynes, UK*References*: <ecop6e$308$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

madhukarrapaka at yahoo.com wrote: > Actually i want to display a 3D plot of an Intensity in a Cylidrical volume. The intensity is calculated as follows. > > I=P/2*Pi*r*L .; where P=10.3,L=0.45,r=dist. ,r0=0.025,T=0.9,d=0.1643; As it at already been said, do NOT use CAPITAL letters as variable name. For instance, this following attempt to define a variable called capital I is a very nasty one: I = (P/2)*Pi*r*L --> Set::"wrsym" : "Symbol (I) is Protected. Capital I is already defined as Sqrt[-1]. Basically, you just tried to change the value of the imaginary unit, unit that is of quite importance in mathematics in particular and in sciences in general. You definitely should spend some time reading the documentation. http://documents.wolfram.com/mathematica/functions/I Regards, Jean-Marc