Re: Curl and Div problems

*To*: mathgroup at smc.vnet.net*Subject*: [mg115504] Re: Curl and Div problems*From*: Andrea <btlgs2000 at gmail.com>*Date*: Thu, 13 Jan 2011 03:25:04 -0500 (EST)*References*: <igjr0p$928$1@smc.vnet.net>

On 12 Gen, 10:07, sean k <seaninso... at gmail.com> 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? The default cartesian coordinates in vectoranalysis package are Xx, Yy, Zz. So if you write In: Div[{Xx^2 Yy, Xx Zz, Xx^2 Yy^3}] you obtain the correct answer Out: 2 Xx Yy. If you want you can change coordinates names using In: SetCoordinates [ Cartesian[x, y, z] ] After doing this your code will work. In:Div[{x^2 y, x z, x^2 y^3}] Out:2 x y Andrea