Re: What is happening here? (TagSet)
- To: mathgroup at smc.vnet.net
- Subject: [mg28074] Re: What is happening here? (TagSet)
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Fri, 30 Mar 2001 04:12:25 -0500 (EST)
- Organization: Universitaet Leipzig
- References: <99chu9$8eq@smc.vnet.net> <99f5b2$bf8@smc.vnet.net> <99ut4h$62s@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Hi, just try it. Since Re[] and Im[] are different functions there is no build in rule that say Re[z_]/; Im[z]==0 :=z and so you should define Re[] and Im[]. Regards Jens John Todd wrote: > > On 23 Mar 2001 04:34:26 -0500, Jens-Peer Kuska > <kuska at informatik.uni-leipzig.de> wrote: > > One other quick related question: > > if I do the following: > > x/:Im[x]=0; > y/:Im[y]=0; > > all of the equations and problems work just as well as if I had done > this: > > x/:Im[x]=0; > y/:Im[y]=0; > x/:Re[x]=x; > y/:Re[y]=y; > > which makes sense to me, because the last two 'upvalues' for x seem > redundant in my mind, at least from a mathematical viewpoint. Is > there some reason that I should go with the latter form as opposed to > the former, or will the former suffice? > > Thanks, > > JT