Re: Separating real part and imaginary part from each

*To*: mathgroup at smc.vnet.net*Subject*: [mg101247] Re: [mg101189] Separating real part and imaginary part from each*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Sat, 27 Jun 2009 06:07:44 -0400 (EDT)*Reply-to*: hanlonr at cox.net

f[z_] = (a*z + b)/(c*z + d); g = f[x + I*y]; g // ComplexExpand // FullSimplify (a*x + I*a*y + b)/(c*x + I*c*y + d) FullSimplify[ComplexExpand[#]] & /@ (Re[g] + I*Im[g]) ((a*x + b)*(c*x + d) + a*c*y^2)/ (c^2*y^2 + (c*x + d)^2) + (I*(a*d*y - b*c*y))/(c^2*y^2 + (c*x + d)^2) % == %% // Simplify True Bob Hanlon ---- Alexander <alexander.erlich at gmail.com> 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