Re: Vectors,Norms and assumptions

• To: mathgroup at smc.vnet.net
• Subject: [mg82764] Re: Vectors,Norms and assumptions
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Tue, 30 Oct 2007 05:43:39 -0500 (EST)
• Organization: Uni Leipzig
• References: <fg6rjo\$e89\$1@smc.vnet.net>

```Hi,

for Integrate[] there is a Option Assumptions->Element[{av1,av2},Reals]
and for FullSimplify[]/Simplify[] there is a second argument  for
the assymptions and there a two functions Assuming[] and Refine[]
to restrict the symbols to Reals or Integers .. and you can use the
global variable \$Assumptions to set the domains global.

Regards
Jens

apsi wrote:
> Hello,
> I have a question in mathematica (actually 3).
>
> 1. Let v be v={av1,av2} , then Norm[v]=Sqrt[Abs[av1]^2 + Abs[av2]^2]
> Q: How do indicate to mathematica that av1 and av2 belong to reals?
>
> 2. On a similar note, i have
> n={an1,an2}
> a={aa1,aa2}
> (*an1,an2,aa1,aa2 are all reals*)
> x=Norm[y(n-a)]
>>> Sqrt[Abs[(-aa1 + an1) y]^2 + Abs[(-aa2 + an2) y]^2]
>
> Once again, how do i indicate that y ,an1,an2,aa1,aa2 are reals?
>
> Thank you for your time and help.
> Rgds
> Bveo
>
>

```

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