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RE: how to specify something is "real"

  • To: mathgroup at smc.vnet.net
  • Subject: [mg43170] RE: [mg43161] how to specify something is "real"
  • From: "David Park" <djmp at earthlink.net>
  • Date: Sat, 16 Aug 2003 02:53:52 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

K,

When it comes to Mathematica there are very few dumb questions!

If you use ComplexExpand on an expression, it assumes that all variables are
real, or you can supply a list of variables that are not real. Look it up in
Help. Sometimes you may also want to restrict the TargetFunctions. Sometimes
I think ComplexExpand should be called ComplexSimplify. If you are doing
complex analysis you will probably be using it all the time.

Cos[x]
Conjugate[%]
% // ComplexExpand

Cos[x]
Conjugate[Cos[x]]
Cos[x]

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

From: pgp [mailto:bla at bla.com]
To: mathgroup at smc.vnet.net

Hi,
This is probably a dumb question, but I was trying to use Conjugate[] on an
expression that contains terms like Cos[x], and mathematica doesn't take it
for granted that Cos[x] is real, and hence the end result contain lots of
Conjugate's that can't be reduced.
Could someone tell me if it's possible to tell mathematica which parts of
the expressions are supposed to be real, so it'll get rid of all those
Conjugates?
Thanks a lot.
-K



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