Re: complex analysis problem in mathematica 3.0

*To*: mathgroup at smc.vnet.net*Subject*: [mg48475] Re: [mg48459] complex analysis problem in mathematica 3.0*From*: Hugh Walker <hwalker at gvtc.com>*Date*: Tue, 1 Jun 2004 03:02:50 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

On Sunday, May 30, 2004, at 11:13 PM, BranasMan wrote: > i have a complex function: > > H(s)=1 / (s^3 + 2s^2 + 2s + 1) > > whan i replace "s" with j*w (j=sqrt(-1)) i get: > > H=1 / (1 + j2w -2w^2 - jw^3) > > i would like to get that function in shape of : > H=something + j*something_else i.e. the complex > and real part apart. > > i played with Re and Im,but it seems that the fact that > "w" is a variable confuses mathematica?! > > i would reeeealy appreciate any help,and maybe perhaps some > links for me to learn to use mathematica better. Here is one way: h = (1 / (s^3 + 2s^2 + 2s + 1) /. s -> I w) // ComplexExpand ========== Hugh Walker Gnarly Oaks