Re: partial derivative of a sum
- To: mathgroup at smc.vnet.net
- Subject: [mg59825] Re: partial derivative of a sum
- From: "Vladislav" <kazimir04 at yahoo.co.uk>
- Date: Tue, 23 Aug 2005 04:51:19 -0400 (EDT)
- References: <de9cut$q78$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
As I give
ClearAll[n, l]
D[Sum[n[i] l[i], {i, 1, Infinity}], n[10]]
my MATHEMATICA (version 5.0) gives
8::indet: Indeterminate expression 0\8 encountered.8::indet:
Indeterminate expression 0\8 encountered.
Indeterminate
It means that Wolfram has partially corrected this. Take
Sum[n[i] l[i], {i, 1, Infinity}] // FullForm and you will see the form
MATHEMATICA treats the argument in D[.,n[10]]. When applied, D can not
find n[10] and returns 0 in your version.I