Re: Question about Hold

*To*: mathgroup at smc.vnet.net*Subject*: [mg48833] Re: Question about Hold*From*: drbob at bigfoot.com (Bobby R. Treat)*Date*: Fri, 18 Jun 2004 02:13:02 -0400 (EDT)*References*: <carjrn$r76$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

A few questions: 1) Why write A*A as if that's different from A^2? (It isn't.) 2) Why use Hold[A*A] if you want the argument evaluated? 3) What do you want Commute[Hold[A*A],B] to evaluate to? (Commute[A,C], I suppose.) 4) What have you done to make it happen? Just Commute[A,B]=C? Or something else. 5) Are we mind-readers? Bobby Daohua Song <ds2081 at columbia.edu> wrote in message news:<carjrn$r76$1 at smc.vnet.net>... > Hi,evryone, > I define a commute relation for quantum operators,i fact i learn this > from the forum.Here is the problem. > Commute[A,B]=C. > Commute[A^2,B], i try to use Hold[A*A] instead of A^2, then mathematica > even won't evaluate it.! > Any suggestion to work on the power commutation? > Thanks > Daohua