Re: Dealing with sums
- To: mathgroup at smc.vnet.net
- Subject: [mg41004] Re: Dealing with sums
- From: "Bill Bertram" <wkb at ansto.gov.au>
- Date: Mon, 28 Apr 2003 02:31:13 -0400 (EDT)
- Organization: Australian Nuclear Science and Technology Organisation
- References: <b8g114$pg5$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
"Stepan Yakovenko" <yakovenko at ngs.ru> wrote in message news:b8g114$pg5$1 at smc.vnet.net... > HI! > > I want to get a derivative in terms of KroneckerDelta function: > > \!\(\[PartialD]\_\(a\_3\)\(\[Sum]\+\(i = 0\)\%N a\_i\)\) > > But I get 0. > > Is there a way to do it in Mathematica ? Hi Stepan, No, Idon't think Mathematica can do it in terms of a Kronecker delta because the result is more like a discrete step function. The derivative wrt a[[i]] is 1 for all i <= N and 0 for i >N. Cheers, Bill