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/