smart change of variables?

*To*: mathgroup at smc.vnet.net*Subject*: [mg87695] smart change of variables?*From*: Barrow <GRseminar at gmail.com>*Date*: Tue, 15 Apr 2008 06:51:07 -0400 (EDT)

Dear all, I have a arithmetic problem. I have an expression expr = (p1 + 2*p2)*(k1 + 2*k2) where p1 + p2 = k1 + k2 I wanna make the following change of variables, s = (p1 + p2)^2 t = (p1 - k1)^2 u = (p1 - k2)^2 Is it possible to tell Mathematica to express expr in terms of s, t, and u automatically? Thanks so much. any ideas would be appreciated. Sincerely Barrow

**Follow-Ups**:**Re: smart change of variables?***From:*Daniel Lichtblau <danl@wolfram.com>

**Re: smart change of variables?***From:*"W_Craig Carter" <ccarter@mit.edu>