Re: symbolic complex expressions

*To*: mathgroup at smc.vnet.net*Subject*: [mg53683] Re: [mg53637] symbolic complex expressions*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Sat, 22 Jan 2005 03:52:32 -0500 (EST)*Reply-to*: hanlonr at cox.net*Sender*: owner-wri-mathgroup at wolfram.com

ComplexExpand[Abs[x+I*y]] Sqrt[x^2 + y^2] ComplexExpand[x/(x+I*y)] x^2/(x^2 + y^2) - (I*x*y)/(x^2 + y^2) Bob Hanlon > > From: frankdeicke at gmx.de (Frank) To: mathgroup at smc.vnet.net > Date: 2005/01/21 Fri AM 06:35:44 EST > To: mathgroup at smc.vnet.net > Subject: [mg53683] [mg53637] symbolic complex expressions > > Hi, > > I've 2 question with mathematica using symbolic complex expressions. > > - Is there a possibility to make from i.e. |x + I y| -> sprt(x^2+y^2) > if x and y are Real. Abs[] doesn't work? > > > - You've a fraction like this x/(x + I y) and you want to eliminate > the complex expression in the denominator. > i.e. doing something like this: x/(x + Iy)*(x - I y)/(x - I y) -> (x^2 > - I x y)/(x^2+y^2) > > How do you do this with mathematica? > > Thanks, > > Frank > >