Searching for embedded zeros in list

*To*: mathgroup at smc.vnet.net*Subject*: [mg32136] Searching for embedded zeros in list*From*: "Coleman, Mark" <mark.coleman at dri-wefa.com>*Date*: Sat, 29 Dec 2001 00:46:57 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

Greetings, Can anyone suggest an efficient/elegant way of checking a list for 'embedded' zeros. By embedded I mean the occurence of one or more zeros between two non-zero elements (note: zeros at the ends of the list are not relevant). For instance, the following lists all contain embedded zeros: a={0.98,0.87,0.0,0.5,0.25} b={0.9,0.0,0.0,0.0,0.0,0.0,0.05} c={0.75,0.42,0.10,0.0,0.03} while this list does not d={0.0,0.90,0.75,0.42,0.25,0.0} By way of background, I am working on a problem involving estimating generators for Markov transition matrices. One condition that ensures that a generator *does not* exist is the presence of inaccessible states in any row of the matrix. Thus one need only find a single occurance of an inaccessible state to show that a generator does not exist. Hence the code need only locate one such state, not all of them. The Mathematica code I've written for this problem does work, but it is hardly "elegant". Any help would be much appreciated! Best regards, -Mark