Re: product formula in mathematica

*To*: mathgroup at smc.vnet.net*Subject*: [mg68782] Re: product formula in mathematica*From*: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>*Date*: Fri, 18 Aug 2006 03:12:39 -0400 (EDT)*Organization*: The Open University, Milton Keynes, UK*References*: <ec19d4$oie$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

frou wrote: > Hi I am interested in doing a product over a set of indices that are > not continuous > Product [ f(x_i) , { x_i, 1,3,4,9}] Is this possible it appears > that the iterator wouldonly take sequences such as 1...10 etc. Times @@ MapThread[f[Subscript[x, #1]] & , {{1, 3, 4, 9}}] --> f[Subscript[x, 1]]*f[Subscript[x, 3]]*f[Subscript[x, 4]]*f[Subscript[x, 9]] Times @@ MapThread[f[x[#1]] & , {{1, 3, 4, 9}}] --> f[x[1]]*f[x[3]]*f[x[4]]*f[x[9]] http://documents.wolfram.com/mathematica/functions/Apply http://documents.wolfram.com/mathematica/functions/MapThread HTH, Jean-Marc