Re: UpSetDelayed and N

*To*: mathgroup at smc.vnet.net*Subject*: [mg57138] Re: [mg57128] UpSetDelayed and N*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Tue, 17 May 2005 01:20:01 -0400 (EDT)*References*: <200505170135.VAA23186@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

On 17 May 2005, at 10:35, François Wirion wrote: > Hello, > > I have done the following in Mathematica: > P[N[x]] ^:= 0 > If I put in > P[N[x]] > it returns > 0 > as expected. > > However, I haven't been able to find where this definition is stored. > Calling the following for P > > OwnValues[P] > DownValues[P] > UpValues[P] > SubValues[P] > NValues[P] > DefaultValues[P] > FormatValues[P] > Messages[P] > > and N > > OwnValues[N] > DownValues[N] > UpValues[N] > SubValues[N] > NValues[N] > DefaultValues[N] > FormatValues[N] > Messages[N] > > returns mostly empty lists, but no definition that says that P[N[x]] is > 0. Where then would this be stored? > > Thank you for any help or advice, > > François Wirion It is stored as an Upvalue of x. P[N[x]] ^:= 0 UpValues[x] {HoldPattern[P(x)]:>0} The reason is of course that N[x] returns x. Andrzej Kozlowski

**References**:**UpSetDelayed and N***From:*"François Wirion" <muthaluva@gmail.com>