Re: Curl and Div problems

*To*: mathgroup at smc.vnet.net*Subject*: [mg115501] Re: Curl and Div problems*From*: "Kevin J. McCann" <Kevin.McCann at umbc.edu>*Date*: Thu, 13 Jan 2011 03:24:27 -0500 (EST)*References*: <igjr0p$928$1@smc.vnet.net>

I also noticed this. It seems that Curl is defined in the basic Mathematica commands; hence, the red indicates that you have defined the function twice. As far as your Div example goes, you haven't specified the variables that Div is supposed to use for differentiation. Try this before the Div. SetCoordinates[Cartesian[x,y,z]] If you don't do this, Mathematica assumes the variables are {Xx,Yy,Zz}. Kevin On 1/12/2011 4:07 AM, sean k wrote: > I'm having problems with VectorAnalysis package. > > Within the documentation center, the package loads and works fine. > > But in a notebook, it seems to highlight Curl in red and neither Div > or Curl works properly. > > Needs["VectorAnalysis`"] > > {D[x^2 y, x] + D[ x z, y] + D[ x^2 y^3, z]} > > Div[{x^2 y, x z, x^2 y^3}] > > gives different answers. > > {2 x y} > 0 > > > Curl[{x^2 y, x z, x^2 y^3}] > > gives > > {0,0,0} > > > I'm on windows vista home edition, 64 bit, Mathematica 8.0. > > Does anyone else have this problem? > >