Re: symbolic complex expressions

*To*: mathgroup at smc.vnet.net*Subject*: [mg53677] Re: symbolic complex expressions*From*: "Scout" <user at domain.com>*Date*: Sat, 22 Jan 2005 03:52:15 -0500 (EST)*References*: <csqqmb$1lk$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi, "Frank" > 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? > In[]:= ComplexExpand[Abs[x + I y], TargetFunctions->{Re,Im}] This forces Math. to assume both x and y are real. > > - 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) > As above... In[]:= ComplexExpand[x/(x + I y), TargetFunctions->{Re,Im}] Bye, ~Scout~