Re: Algebraic substitutions. HOW?
- To: mathgroup at smc.vnet.net
- Subject: [mg17717] Re: Algebraic substitutions. HOW?
- From: phbrf at t-online.de (Peter Breitfeld)
- Date: Sun, 23 May 1999 02:25:31 -0400
- Organization: das ist ein breites Feld ...
- References: <7i35a6$bfd@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Alessio Massaro <alessio at mail.cern.ch> schrieb: > Hi, > > say I have an expression like (a^2)/(b^2) and I want to change it by > introducing c:=a/b in order to obtain c^2. > > Euivalent exaple: h^3/t^2 -> (z:=h^2/t^2) -> z*h > > How do I get Mathematica to perform this kind of algebraic > substitutions (on complex formulas)? > Alessio, I think all you can do is something like this: In[1]:= a^2/b^2 /. a->c b Out[1]= c^2 In[2]:= h^3/t^2 /. t->h/Sqrt[z] Out[2]= h z You can't do eg. a^2/b^2 /. a/b->z because the pattern a/b doesn't match anything in the FullForm of a^2/b^2, which is Times[Power[a,2],Power[b,-2]] Es gruesst Peter -- =--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--=--= Peter Breitfeld, Saulgau, Germany PGP public key: 08548045