[GiNaC-list] question about quantum operator algebra

[Canhua]

> Date: Sat, 5 May 2007 11:13:49 +0200 (CEST)
> From: Chris.Dams at mi.infn.it
> Subject: Re: [GiNaC-list] question about quantum operator algebra
> To: "GiNaC discussion list" <ginac-list at ginac.de>
> You can declare those operators as noncommutative symbols. I assume that
> you are using version 1.3.x. Then it goes as e.g.,
>
>    const unsigned my_tinfo = 2;
>    symbol a("a", return_types::noncommutative, my_tinfo);
>    symbol adag("adag", return_types::noncommutative, my_tinfo);
>    H = epsilon*adag*a;
>    ex commu = a*H - H*a
>    commu = rewrite_operators(commu);
>
> The global constant my_tinfo is arbitrary, but for safety it should not be
> one that is already in use (see
> http://www.ginac.de/viewcvs/GiNaC/ginac/tinfos.h?hideattic=0&rev=1.27.2.3&view=markup).
> You would have to define the function rewrite_operators yourself. It could
> be something like
>
> ex rewrite_operators(const ex &x)
> {  if (is_a<ncmul>(x))
>    {  ... constructing the result of rewriting is done here ...

Sorry, but I have no idea what goes here. Could you show me somewhere
to find examples? Thank you.

>       return result;
>    }
>    else
>       return x.map(rewrite_operators);
> }

Best regards,

Can-Hua Chen