Re: Simplify this complex expression?
- To: mathgroup at smc.vnet.net
- Subject: [mg30893] Re: Simplify this complex expression?
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Sun, 23 Sep 2001 02:16:33 -0400 (EDT)
- References: <9oet9v$ilh$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Aram, expr= Sqrt[-(lam/Im[(d1*lam - f*lam + I*Pi*w0^2)/(d1*d2*lam - d2*f*lam - f^2*lam + I*d2*Pi*w0^2)])]/Sqrt[Pi]; ComplexExpand//@expr (Sqrt[1/f^2]*Sqrt[1/w0^2]*Abs[d1*d2*lam - d2*f*lam - f^2*lam + I*d2*Pi*w0^2])/Pi Simplify[%,And[d1>0,d2>0,f>0,lam>0,w0>0]] Abs[d1*d2*lam - d2*f*lam - f^2*lam + I*d2*Pi*w0^2]/ (f*Pi*w0) ComplexExpand[%, TargetFunctions-> {Re,Im}] Sqrt[(d1*d2*lam - d2*f*lam - f^2*lam)^2 + d2^2*Pi^2*w0^4]/ (f*Pi*w0) -- Allan --------------------- Allan Hayes Mathematica Training and Consulting Leicester UK www.haystack.demon.co.uk hay at haystack.demon.co.uk Voice: +44 (0)116 271 4198 Fax: +44 (0)870 164 0565 "Aram Schiffman" <awacs7 at home.com> wrote in message news:9oet9v$ilh$1 at smc.vnet.net... > Hi, > > I have this expression: > > Sqrt[-(lam/Im[(d1*lam - f*lam + I*Pi*w0^2)/(d1*d2*lam - d2*f*lam - > f^2*lam + > I*d2*Pi*w0^2)])]/Sqrt[Pi] > > and I wish to simplify it. (Or other expressions with essentially the > same structure). All variables are real and positive, so I want the > real parts of Im[...] to go away. > > It's easy enough by hand, but for various reasons I would like > Mathematica to do it for me. > > I had a general idea to somehow map ComplexSimplify through all levels > of the expression, and then work my way (somehow) back to the top > level. Problem is, when I use "Level," the Heads go away; I can't > automate the reverse process. I can't think of any other approach to > try. > > Is there a way to do this thing? > > Thanks in advance, > > Aram Schiffman >