Re: Finding Position in an ordered list

*To*: mathgroup at smc.vnet.net*Subject*: [mg57737] Re: Finding Position in an ordered list*From*: dh <dh at metrohm.ch>*Date*: Tue, 7 Jun 2005 02:03:38 -0400 (EDT)*References*: <d811k4$cch$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi Janos, I think "DiscreteMath`Combinatorica`BinarySearch" is what you are searching for. ?BinarySearch BinarySearch[l, k] searches sorted list l for key k and gives the position of l containing k, if k is present in l. Otherwise, if k is absent in l, the function returns (p + 1/2) where k falls between the elements of l in positions p and p+1. BinarySearch[l, k, f] gives the position of k in the list obtained from l by applying f to each element in l. sincerely, Daniel janostothmeister at gmail.com wrote: > I wonder if it is possible to use the knowledge > that a list in which I am looking for the position > of an element is ordered. I want a quicker solution then e.g. > lis={ac,dmk,rfg,sty,zxxer} > Position[lis,sty] > > I am certainly interested in longer lists... > > Thank you, > > Janos > >