Re: Skipping Elements in Sum

*To*: mathgroup at smc.vnet.net*Subject*: [mg61104] Re: Skipping Elements in Sum*From*: Bill Rowe <readnewsciv at earthlink.net>*Date*: Mon, 10 Oct 2005 02:40:06 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

On 10/9/05 at 1:36 AM, qcadesigner at gmail.com wrote: >Does anyone know how to skip elements using the mathematica sum? >e.g. take the sum of all i, where i not equal to j. Yes. One way to do this with the Sum function would be to use the KroneckerDelta function as follows: Sum[Subscript[a, n](1 - KroneckerDelta[n, 3]), {n, 5}] Another way to create the same sum would be Total[Table[Subscript[a, n], {n, 5}][[Complement[ Range[5], {3}]]]] and there are many other ways to achieve the same result. Which is best depends on exactly what you are trying to accomplish. -- To reply via email subtract one hundred and four