Re: Problems evaluating Grad
- To: mathgroup at smc.vnet.net
- Subject: [mg39393] Re: Problems evaluating Grad
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Fri, 14 Feb 2003 03:17:34 -0500 (EST)
- Organization: Universitaet Leipzig
- References: <b2fpvg$k66$1@smc.vnet.net>
- Reply-to: kuska at informatik.uni-leipzig.de
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
the answer of
In[]:= <<Calculus`VectorAnalysis`
In[]:= f[x_,y_]:=x+y;
Grad[f[a,b]]
is
Out[]={0,0,0}
because a, and b don't depend on x,y,z
If Mathematica does not find a rule, that apply to
an expression it leave the expression unchanged
and if nothing happen you have rpbably not loaded
the Calculus`VectorAnalysis` package.
Regards
Jens
Konrad Den Ende wrote:
>
> I'd like to detrmine Grad to a function so i go:
> <<Calculus`VectorAnalysis`
> f[x_,y_]:=x+y
>
> Grad[f[a,b]]
>
> I get no errors, but the answer is simply the same thing
> that i asked, as if no computation was done. What do i
> do wrong?
>
> Also - when i evaluated the examples in Help i got the same
> behavior. The answer that already is there gets exchanged
> to something else upon my evaluation. Namely, the question
> itself. What is that?!
>
> --
>
> Vänligen
> Konrad
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