Re: Problem with D and Abs
- To: mathgroup at smc.vnet.net
- Subject: [mg61014] Re: Problem with D and Abs
- From: Daniele Lupo <danwolf80_no_spam_ at libero.it>
- Date: Fri, 7 Oct 2005 03:38:04 -0400 (EDT)
- References: <di1m0c$2r8$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Il Wed, 5 Oct 2005 23:01:32 +0000 (UTC), Daniele Lupo ha scritto: > 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 Thanks to all... All these hints works for me!!! :-) Daniele