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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


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