Re: Symbolic complex conjugation
- To: mathgroup at smc.vnet.net
- Subject: [mg26153] Re: Symbolic complex conjugation
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Thu, 30 Nov 2000 01:03:59 -0500 (EST)
- Organization: Universitaet Leipzig
- References: <8vvpo5$34g@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Hi, > Suppose one wishes to do symbolic complex conjugation on a complicated > symbolic expression in which all symbols are assumed purely real -- that > is, given a symbolic expression of arbitrary complexity with multiple > instances of I occuring inside it, change every instance of I to -I, and > nothing more. > > The best approach I'm aware of seems to be the method described in the > 4.0 Help files, namely > > new_expr = old_expr /. Complex[0, n_] -> -Complex[0, n] > > Is there a better approach than this? No. > > And, for educational purposes, can someone explain how and why this > approach works? In particular, why isn't the rule something like > > Complex[a_, b_] -> Complex[a, -b] > > Is the "0" significant? Is the "n" supposed to be integer? Yes because: FullForm[a + I*b] is Plus[a, Times[Complex[0, 1], b]] Complex[] is always a number, you cant have Copmplex[a_Symbol,b_Symbol] and so your symbolic expression include only I or Complex[0,1] and no other objects with head Complex[]. Regards Jens