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Re: Declaring real variables using Element

  • To: mathgroup at smc.vnet.net
  • Subject: [mg63464] Re: [mg63427] Declaring real variables using Element
  • From: "David Park" <djmp at earthlink.net>
  • Date: Sun, 1 Jan 2006 01:16:22 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

Gideon,

Simply use ComplexExpand, which assumes that all symbols are real.

Conjugate[\[ImaginaryI] s] // ComplexExpand
(-I)*s

For some reason, beginners overlook the ComplexExpand command when starting
to work with complex numbers and functions. You will almost always have to
use ComplexExpand. Check it out in Help and also notice the Options.

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/



From: GidiL [mailto:gidienator at gmail.com]
To: mathgroup at smc.vnet.net


Hello to all!

I am trying to declare the variable S to be real, using the Element
command:
Element[S, Reals]

Next I calculate the complex conjugate of IS (I is the imaginary unit)
Conjugate[\[ImaginaryI] S]

The result I get is
-\[ImaginaryI] Conjugate[S]

 which should have been -IS. Why does it not recognise S as a real
variable?

I would appreciate any help.

Thanks,
Gideon



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