Re: On Defining Functions Symmetric wrt Some Indices
- To: mathgroup at smc.vnet.net
- Subject: [mg34337] Re: On Defining Functions Symmetric wrt Some Indices
- From: lzhao at ihw.com.cn (Instanton)
- Date: Wed, 15 May 2002 03:35:36 -0400 (EDT)
- References: <abqiln$9vj$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
f[a_,b_,c_]:=f[a,c,b]/; !OrderedQ[b,c] Alexei Akolzin <akolzine at uiuc.edu> wrote in message news:<abqiln$9vj$1 at smc.vnet.net>... > Hello, > > For the purposes of formula simplification I need to specify that some > function "f" is symmetric upon SOME of its indices. For example, > f[a,b,c] == f[a,c,b] but NOT equal to f[b,a,c]. > > The proposed command SetAttribute[f,Orderless] makes the function > symmetric wrt ALL of its indices, which I want to avoid. > > Is there is a way to neatly solve this problem? > > Thanks. > > Alexei.