A week of all-day technical Working Group meetings can be pretty tiring.
ncm - your article didn't mention which programming language to use, and although it's clear the approach I posted isn't what you were thinking of, it doesn't depend on any external libraries. It doesn't need to: dates and times are first-class native datatypes in XPath 2 and hence XQuery.
Date measurement algorithms, like binary search functions, are things that many (most?) people find difficult, and there's a good reason to encourage people to use libraries.