Re: Why does Derivative fail in this case?

*To*: mathgroup at smc.vnet.net*Subject*: [mg96598] Re: Why does Derivative fail in this case?*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Mon, 16 Feb 2009 16:42:59 -0500 (EST)*Organization*: Uni Leipzig*References*: <gnbkcl$3ej$1@smc.vnet.net>*Reply-to*: kuska at informatik.uni-leipzig.de

Hi, try: g = f[#1, #2]*f[#1, #2] &; And why SlotSequence[1] is different from Slot[1] is self-explanatory Regards Jens Aaron Fude wrote: > Hi, > > This example is self-explanatory: > > f[x_, y_] := x y > g = f[##]*f[##] &; > h = Derivative[1, 0][g]; > g[x, y] > h[x, y] > > I should expect that h[x, y] is 2 x y^2, but instead it is zero. How > come? > > Version 6.0 > > Many thanks in advance, > > Aaron >