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Re: symbolic complex expressions

• To: mathgroup at smc.vnet.net
• Subject: [mg53667] Re: [mg53637] symbolic complex expressions
• From: Murray Eisenberg <murray at math.umass.edu>
• Date: Sat, 22 Jan 2005 03:51:49 -0500 (EST)
• Organization: Mathematics & Statistics, Univ. of Mass./Amherst
• References: <200501211135.GAA01324@smc.vnet.net>
• Reply-to: murray at math.umass.edu
• Sender: owner-wri-mathgroup at wolfram.com

ComplexExpand[Abs[x + I y]]

ComplexExpand[x/(x + I y)]

Frank wrote:
> 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
> 
> 

-- 
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305

• References:
  • symbolic complex expressions
    • From: frankdeicke@gmx.de (Frank)