Re: symbolic and indefinite differentiation

*To*: mathgroup at smc.vnet.net*Subject*: [mg35450] Re: symbolic and indefinite differentiation*From*: Francois Coppex <francoiscoppex at hotmail.com>*Date*: Sat, 13 Jul 2002 03:48:21 -0400 (EDT)*References*: <agjj4k$253$1@smc.vnet.net> <agm431$58n$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

> expr = Sum[a[k]*x^k, {k, 1, p}]; > D[expr, x] /. HoldPattern[Sum[a_, b__]] :> Sum[Evaluate[a], b] > > ??? I think that what he's trying to do is rather something like p = 100; Array[x, p]; f = Sum[x[i]^2, {i, 1, p}]; j = 43; D[f, x[j]] but leaving p and j undefined.