Re: Separating real part and imaginary part from each

*To*: mathgroup at smc.vnet.net*Subject*: [mg101216] Re: [mg101189] Separating real part and imaginary part from each*From*: Murray Eisenberg <murray at math.umass.edu>*Date*: Sat, 27 Jun 2009 06:02:00 -0400 (EDT)*Organization*: Mathematics & Statistics, Univ. of Mass./Amherst*References*: <200906261050.GAA18233@smc.vnet.net>*Reply-to*: murray at math.umass.edu

ComplexExpand is your friend in such situations. (For reasons I don't know, it seems unknown to too many users.) And of course you must use correct Mathematica syntax (but no reason for those explicit * signs): f[z_] := (a z + b)/(c z + d) ComplexExpand[ f[x + I y] ] Alexander wrote: > Hi, > > suppose I have the expression > > f(z) = (a*z+b) / (c*z+d) with z=x+I*y > > I did the calculation by hand and was able to separate real part fom > imag. part to obtain something like this: > > g=f(x+I*y) = Re(g) + I * Im(g) > > But I don't know how to do this in Mathematica. I tried FullSimplify, > Together, Apart, they didn't work. Can you help me? > > Alexander > -- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2859 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305

**References**:**Separating real part and imaginary part from each other***From:*Alexander <alexander.erlich@gmail.com>