Re: Mathmatica Problem...

*To*: mathgroup at smc.vnet.net*Subject*: [mg14344] Re: Mathmatica Problem...*From*: "Allan Hayes" <hay at haystack.demon.co.uk>*Date*: Thu, 15 Oct 1998 00:28:47 -0400*References*: <6vuqt7$8ju@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Mr D.J. Winstanley wrote in message <6vuqt7$8ju at smc.vnet.net>... > >Dear mathgroup, > >We have just upgraded to release 3 of mathematica and we have found a >problem with the Expand function as described in the mathematica >manual. Here is the mathematica 3.0 output... > > >In[3]:= Expand[Cos[x]^3 Sin[x]^2,Trig->True] > >gives > > 3 2 >Out[3]= Cos[x] Sin[x] > > >this is not the answer given in the manual, which is... > > Cos[x] - Cos[3 x] - Cos[5 x] > ------ -------- -------- > 8 16 16 > > >We were led to believe that the new version was compatible with the >previous version. > >Is there a switch to obtain compatibility??? > >Any comments on this would be appreciated. Also who should I send this >to at Wolfram? > >thanks for your help > David, I don't have Mathematica 2.2 anymore - can you give the reference to the manual information that you quote please? I also get cs =Cos[x]^3 Sin[x]^2; Expand[Cos[x]^3 Sin[x]^2,Trig->True] 3 2 Cos[x] Sin[x] But that is what I would expect. The following two evaluations give the result that you quote from the manual (up to multiplying out). TrigReduce[cs] 1 -- (2 Cos[x] - Cos[3 x] - Cos[5 x]) 16 Apart[cs,Trig->True] Cos[x] 1 1 ------ - -- Cos[3 x] - -- Cos[5 x] 8 16 16 ---------------------- Allan Hayes Mathematica Training and Consulting www.haystack.demon.co.uk hay at haystack.demon.co.uk Voice: +44 (0)116 271 4198 Fax: +44 (0)870 164 0565