Series problem

*To*: mathgroup at smc.vnet.net*Subject*: [mg4084] Series problem*From*: f85-tno at telesto.nada.kth.se (Tommy Nordgren)*Date*: Fri, 31 May 1996 01:36:00 -0400*Organization*: Royal Institute of Technology, Stockholm, Sweden*Sender*: owner-wri-mathgroup at wolfram.com

I want to expand the Cosine only in the expression: Cos[b x] Exp[-x^2]/(k^2+x^2) into a taylor series around 0. Computing the series in terms of x don't work, because the exponetial and the divisor will be expanded as well, when the series of the Cosine is multiplied by the other factors. Making the series expansion in terms of b don't work, because Mathematica can't integrate the resulting series expansion in terms of x. Are there any way to handle this except by introducing a new representation for function series. (The problem I'm currently interested in is finding a series for the function f[b_,k_] = Integrate[Cos[b x] Exp[-x^2]/(k^2+x^2),{x,-Infinity,Infinity}], which is valid for small b) -- ------------------------------------------------------------------------- Tommy Nordgren "Home is not where you are born, Royal Institute of Technology but where your heart finds peace." Stockholm Tommy Nordgren - The dying old crone f85-tno at nada.kth.se -------------------------------------------------------------------------- ==== [MESSAGE SEPARATOR] ====