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
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"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