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MathGroup Archive 2004

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Re: Complex Numbers

  • To: mathgroup at smc.vnet.net
  • Subject: [mg47463] Re: Complex Numbers
  • From: "Dana DeLouis" <delouis at bellsouth.net>
  • Date: Tue, 13 Apr 2004 06:26:14 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Just another technique since it was not mentioned...

v = Re[ComplexExpand[Exp[a*I]*Exp[b*I]]]

-Im[Sin[a+b]]+Re[Cos[a+b]]

Refine[v, Element[{a, b},Reals]]

Cos[a+b]

-- 
Dana DeLouis
Windows XP
Mathematica 5.0 for Windows 
delouis at bellsouth.net


= = = = = = = = = = = = = = = = = 
"Alejandro Vizcarra" <gebankos at prodigy.net.mx> wrote in message
news:c5b0tc$7lc$1 at smc.vnet.net...
> Hi,:
>  
> I always have problems when dealing with complex numbers.  How can i
> work with Mathematica in such a way that every expression will
> be considered real unless it is declared explicitly complex (like a =
3 + 4 I ) ?
>  
> For example if I type 
> 
> Re[ComplexExpand[ Exp[a I] Exp[b I]]]
> 
> I get the answer
> 
> -Im[Sin[ a+b]]+Re[Cos[a+b]]
> 
> Instead of simply Cos[a+  b]
> 
> Thnx!
> Alejandro Vizcarra


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