Mathematica 9 is now available
Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2008

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Almost symbolic computations (?)

  • To: mathgroup at smc.vnet.net
  • Subject: [mg90510] Re: Almost symbolic computations (?)
  • From: David Bailey <dave at Remove_Thisdbailey.co.uk>
  • Date: Fri, 11 Jul 2008 02:04:22 -0400 (EDT)
  • References: <g54oim$etu$1@smc.vnet.net>

Barbara Da Vinci wrote:
> Dear MathGroup
> 
> This is an example of the problem
> I'm facing.
> 
> The code
> 
>    Needs["VectorAnalysis`"];
>    Head /@ {ax, ay, az}
>    A = {ax, ay, az};
>      Curl[A]
> 
> returns
> 
> {Symbol, Symbol, Symbol}
> {0, 0, 0}
> 
> Instead, I would get the
> well known symbolic form
> 
> d_y az - d_z ay
> ...
> 
> I have been trying, for
> a while, to perform string
> manipulations but that,
> of course, lays to ashes
> the possibility to recognize
> 
> d_y az + d_y az = 2 d_y az
> 
> and so on.
> 
> Any way to get out of it ?
> 
> Kind regards
> 
> 
> Barbara Da Vinci
> 
Possibly part of the confusion here is that ax (with no space) is a 
variable with a two-letter name, whereas a x (with a space) is a product 
of a with x.

David Bailey
http://www.dbaileyconsultancy.co.uk


  • Prev by Date: Re: How to show tick labels w/o showi the tick marks?
  • Next by Date: Help with "If" statement within "Table"
  • Previous by thread: Re: Almost symbolic computations (?)
  • Next by thread: Re: Almost symbolic computations (?)