Re: Expression transformation
- To: mathgroup at smc.vnet.net
- Subject: [mg59308] Re: [mg59268] Expression transformation
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Fri, 5 Aug 2005 01:21:45 -0400 (EDT)
- Reply-to: hanlonr at cox.net
- Sender: owner-wri-mathgroup at wolfram.com
expr=Exp[-x]+(a+b Exp[-x])/c; Collect[expr,E^-x] a/c + (b/c + 1)/E^x Collect[expr//Simplify,E^-x] a/c + (b + c)/(E^x*c) Collect[c*expr//Simplify,E^-x]/c (a + (b + c)/E^x)/c expr=(1-Exp[u/(kT)])/Exp[u/(kT)]; expr//Simplify -1 + E^(-(u/kT)) Bob Hanlon > > From: mumbojumbo <mjumbo at gmail.com> To: mathgroup at smc.vnet.net > Date: 2005/08/04 Thu AM 02:07:52 EDT > Subject: [mg59308] [mg59268] Expression transformation > > Dear forum, > > How can I persuade Mathematica to transform the expression > Exp(-x)+(a+b Exp[-x])/c > to the form > (a+(b+c)Exp(-x))/c > > I have tried Together[...] and Simplify, but I always get > (b + c + a*E^x)/(c*E^x) > It looks like Mathematica is silently transforming Exp[-x] to > 1/Exp[x]. How can I disable this transformation? > > I am asking because in applications some equivalent forms are more > equivalent than others e.g. Exp[-u/(kT)]-1 is considered a proper form, > while (1- Exp[u/(kT)])/Exp[u/(kT)] is not. > > Thanks, Yuri. > > mailto:mjumbo at gmail.com > >