Re: BracketingBar for output
- To: mathgroup at smc.vnet.net
- Subject: [mg15826] Re: BracketingBar for output
- From: phbrf at t-online.de (Peter Breitfeld)
- Date: Mon, 8 Feb 1999 03:25:50 -0500 (EST)
- Organization: das ist ein breites Feld ...
- References: <79e86b$96l@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Peter Breitfeld <phbrf at t-online.de> schrieb:
> In my "personal package" I have the function Betrag[x_]:=Sqrt[x.x]
>
> Now I want that in cases where this function can't be evaluated, the
> output in StandardForm is displayes as |x|. (left and right
> BracketingBar, these symbols you get when entering `ESC l| ESC' and
> `ESC r| ESC'.
I want to thank all who gave me very helpful hints to solve this
problem.
I now use the following definitions:
Betrag=BracketingBar
BracketingBar[x_/;(VectorQ[x]&&(Or @@ Map[NumericQ,x]))]:=Sqrt[x.x]
this works really great:
Betrag[x] shows |x|
Betrag[{2,2,1}] shows 3
Betrag[{a,a,1}] shows Sqrt[1+2a^2]
and I can use the Output for Input, eg: |x|/.x->{1,2,2} shows 3
Thanks again to all!
es gruesst
Peter
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Peter Breitfeld, Saulgau, Germany (PGP public key: 08548045)