Re: transforming exponential of sums into product of exponentials

*To*: mathgroup at smc.vnet.net*Subject*: [mg48670] Re: transforming exponential of sums into product of exponentials*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Thu, 10 Jun 2004 02:43:05 -0400 (EDT)*Organization*: Universitaet Leipzig*References*: <ca6igm$j2s$1@smc.vnet.net>*Reply-to*: kuska at informatik.uni-leipzig.de*Sender*: owner-wri-mathgroup at wolfram.com

Hi, it does it because it also evaluate 2*2 to 4. You must use a Hold[] to prevent the simplifications Exp[x + y] /. Exp[a_ + b_] :> Hold[Exp[a]Exp[b]] Regards Jens Karim Mehadhebi wrote: > > Dear All, > > I can not understand why Mathmatica refuses to apply rules which transform > exponenials of sums into product of exponentails. > > For instance, > f[x+y] /. f[a_ + b_]-> f[a] f[b] returns f[x] f[y], > whereas > Exp[x+y] /. Exp[a_+b_]->Exp[a]Exp[b] still returns Exp[x+y] > > Any help greatly appreciated