Re: Naming pieces of patterns

*To*: mathgroup at smc.vnet.net*Subject*: [mg29837] Re: Naming pieces of patterns*From*: "Orestis Vantzos" <atelesforos at hotmail.com>*Date*: Fri, 13 Jul 2001 04:19:18 -0400 (EDT)*Organization*: National Technical University of Athens, Greece*References*: <9ijhj3$rhj$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

The Semantica package could help. It was in one of the issues of Mathematica Journal, can't give any more details right now, sorry. Orestis "Cyril Fischer" <fischerc at itam.cas.cz> wrote in message news:9ijhj3$rhj$1 at smc.vnet.net... > How can I as simply as possible use "substitutions" > 1. > -(I/(2 a)) /. I/(2 a) -> A > does not work, while > (I/(2 a)) /. I/(2 a) -> A > works well > > 2. > {(a + b), -(a + b)}/. a + b -> e > gives > {e, -a - b} > instead of {e,-e} > > 3. > {-Sqrt[a + b], 1/Sqrt[a + b]} /. Sqrt[a + b] -> e > gives > {-e,1/Sqrt[a + b]} > > 4. > {I, 2 I, -I} /. I -> J > gives > {J, 2 \[ImaginaryI], -\[ImaginaryI]} > > I know _why_ these cases do not work, but I would like to know, if there > is a possibilty to use a common pattern rule to substitute all > occurences of an expression. > > Thank you, > Cyril Fischer > >