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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
> 
>