Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2005
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2005

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

Search the Archive

Re: Problem with D and Abs

  • To: mathgroup at smc.vnet.net
  • Subject: [mg60990] Re: Problem with D and Abs
  • From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
  • Date: Fri, 7 Oct 2005 03:37:37 -0400 (EDT)
  • Organization: Uni Leipzig
  • References: <di1m0c$2r8$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

FullSimplify[expr,Element[x,Reals] && 
Element[y,Complexes]]

or

Refine[expr,Element[x,Reals] && 
Element[y,Complexes]]

or

Assuming[Element[x,Reals] && Element[y,Complexes], 
expr]

will simplify, evaluate your expression expr and 
handle x as real
and y as complex.

Regards
  Jens

"Daniele Lupo" <danwolf80_no_spam_ at libero.it> 
schrieb im Newsbeitrag 
news:di1m0c$2r8$1 at smc.vnet.net...
| Hi to all.
|
| I've a problem with this expression:
|
| \!\(Abs[\(Conjugate[s11]\ g\_s\)\/\(1 + 
Abs[s11]\^2\ \((\(-1\) + g\_s)\)\)
| - \
| Ã\_0\/\(1 + N\_i\)] - \@\(N\_i\ \((1 - 
Abs[Ã\_0]\^2 + N\_i)\)\)\/\(1 +
| N\_i\)\
| \)
|
|
| I want to have derivative in gs. If I use D, I 
obtain a strange result,
| that invoke Abs'[...], that's not correct, 
naturally.
|
| I've tried to use PiecewiseExpand, but I've a 
problem. In this expression,
| \!\(g\_s\) and \!\(N\_i\) are real, while 
\!\(Ã\_0\) and s11 are complexes.
| I don't know how to create an expansion that 
consider some symbol as real,
| and some other as complex.
|
| How can I do it?
|
| Thanks for your answers.
|
| Daniele
|
| PS I'm using version 5.1, WinXP
| 



  • Prev by Date: Re: Format.m , FortranAssign : weird identifiers for temporary variables
  • Next by Date: FortranForm of Integers and Reals
  • Previous by thread: Re: Problem with D and Abs
  • Next by thread: Re: Problem with D and Abs