Re: Pattern matching partial derivatives

*To*: mathgroup at smc.vnet.net*Subject*: [mg52422] Re: Pattern matching partial derivatives*From*: Nicolas Girard <nicolas.girard at strasbourg.fr>*Date*: Fri, 26 Nov 2004 06:20:28 -0500 (EST)*References*: <co4dsi$l82$1@smc.vnet.net> <co6hoe$nq3$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Le Fri, 26 Nov 2004 06:16:46 +0000, David Bailey a écrit : > Nicolas, > > Yes, getting this output from Mathematica can be a sign of damnation! > > Alternatively, look at this: > > D[f_, x_, Rule[NonConstants, nc_]] // FullForm > > 0 > > If you want to manipulate derivatives in complicated ways, one way is to > use your own notation for a derivative (say dD) which will obviously not > evaluate, and then use dD ->D to get evaluation when you need it. > David, thanks much for the tip, it appears to do the job indeed... still I'm frustrated. Why couldn't we use patterns to manipulate partial derivatives ? How can it be that, as you pointed out, D[f_, x_, Rule[NonConstants, nc_]] // FullForm gives 0 ? This seems crazy to me...