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MathGroup Archive 1999

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Re: Real coefficients in complex numbers

  • To: mathgroup at smc.vnet.net
  • Subject: [mg15799] Re: [mg15734] Real coefficients in complex numbers
  • From: Andrzej Kozlowski <andrzej at tuins.ac.jp>
  • Date: Sun, 7 Feb 1999 02:04:15 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

On Fri, Feb 5, 1999, Gnalle <GNALLE at MMF.ruc.dk> wrote:

>If you are calculations with complex numbers: a + I b How do you state
>that a and b are real? For example I might want to calculate the real
>part of
>
>a + 1/(b + 1/(1/I c + d)) ; Where a,b,c,d are real
>
>Can this be done in a nice way. (Yes, I do know how to do the
>calculation by hand)
>
>
>-- 
>
>			Niels Langager Ellegaard	
>			'http://mmf.ruc.dk/~gnalle/'


In[4]:=
Simplify[ComplexExpand[Re[a + 1/(b + 1/(1/I c + d))],
    TargetFunctions->{Im,Re}]]

                2    2                    2   2    2
        d + b (c  + d ) + a (1 + 2 b d + b  (c  + d ))
Out[4]= ----------------------------------------------
                                2   2    2
                   1 + 2 b d + b  (c  + d )
Andrzej Kozlowski
Toyama International University
JAPAN
http://sigma.tuins.ac.jp/
http://eri2.tuins.ac.jp/



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