Sorry, but coincidentalArthur C Clarke said that it was short for 'Heuristic Algorithm'. Apparently there is also a reference to this in chapter 16 of the book.
(although not sure whether this represents The Sentinel, of the novelisation that came out after the film).
Link
(,
Mon 4 Jun 2007, 17:45,
archived)
(although not sure whether this represents The Sentinel, of the novelisation that came out after the film).
Link