Re: RE: Trigonometric simplification - newbe question

*To*: mathgroup at smc.vnet.net*Subject*: [mg49082] Re: [mg49031] RE: [mg49004] Trigonometric simplification - newbe question*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Wed, 30 Jun 2004 05:34:28 -0400 (EDT)*Reply-to*: hanlonr at cox.net*Sender*: owner-wri-mathgroup at wolfram.com

expr=(4*(2*a*Sin[(n*Pi)/2]-a*Sin[n*Pi]))/(n^2*Pi^2); Simplify[expr, Element[n, Integers]] (8*a*Sin[(n*Pi)/2])/(n^2*Pi^2) If n is even FullSimplify[% /. n->2m, Element[m, Integers]] 0 If n is odd FullSimplify[%% /. n->2m+1, Element[m, Integers]] (8*(-1)^m*a)/(2*Pi*m + Pi)^2 Bob Hanlon > > From: "David Park" <djmp at earthlink.net> To: mathgroup at smc.vnet.net > Date: 2004/06/29 Tue AM 04:50:08 EDT > To: mathgroup at smc.vnet.net > Subject: [mg49082] [mg49031] RE: [mg49004] Trigonometric simplification - newbe question > > Walter, > > Add an assumption to Simplify (In Version 5, at least). > > expr = (4*(2*a*Sin[(n*Pi)/2] - a*Sin[n*Pi]))/(n^2*Pi^2); > > Simplify[expr, n \[Element] Integers] > (8*a*Sin[(n*Pi)/2])/(n^2*Pi^2) > > But I don't know how one would specify in the assumptions that n was an even > integer greater than zero, say. > > David Park > djmp at earthlink.net > http://home.earthlink.net/~djmp/ > > > > From: Christensen [mailto:fedderwi at uni-bremen.de] To: mathgroup at smc.vnet.net > To: mathgroup at smc.vnet.net > > Hi, > > this is a Mathematica newbe question for sure: > > Mathematica comes up with the following result: > > (4*(2*a*Sin[(n*Pi)/2] - a*Sin[n*Pi]))/(n^2*Pi^2) > > Now I have the additional assumption that n is element of > {1,2,3, ...) (and a is real) > > How do I tell Mathematica to take this into consideration and > remove the Sin[n*Pi] term? > > Thanks, > Walter > > Trigonometric simplification - newbe question > > > >