RE: PatternMatching with Dt[]
- To: mathgroup at smc.vnet.net
- Subject: [mg37291] RE: [mg37264] PatternMatching with Dt[]
- From: "Wolf, Hartmut" <Hartmut.Wolf at t-systems.com>
- Date: Tue, 22 Oct 2002 04:47:11 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
>-----Original Message----- >From: Johannes Ludsteck To: mathgroup at smc.vnet.net >[mailto:johannes.ludsteck at wiwi.uni-regensburg.de] >Sent: Monday, October 21, 2002 8:29 AM >To: mathgroup at smc.vnet.net >Subject: [mg37291] [mg37264] PatternMatching with Dt[] > > >I would like to replace Dt[x_] in a complex >expression. For example consider > >Dt[x]/.Dt[arg_]->f[arg] > >where x is a pure Symbol (has no value). >However, Mathematica refuses apply the rule. >Various other attempts, for example >Unevaluted[Dt[arg_]]:>f[arg] >and HoldForm[...] were unsuccessful. > >I managed to circumvent the problem by >Dt[x]/.Dt->fun >However, I were more happy if I understood why the >first attempt was not successful. >Can someone explain? > >Best regards, > Johannes Ludsteck Johannes, Dt[x] /. HoldPattern[Dt[arg_]] -> f[arg] .... Dt[arg_] Dt[arg]*Derivative[1, 0][Pattern][arg, _] ....the total derivative of arg_ ! -- Hartmut