On 26/03/2015 12:35, Svein Erling Tysvær
svein.erling.tysv...@kreftregisteret.no [firebird-support] wrote:
Here, I find that
SELECT CAST(123456789.12345678 as decimal) FROM RDB$DATABASE
succeeds, whereas
SELECT CAST(123456789.123456789 as decimal) FROM RDB$DATABASE
fails. I don't know why.
Once Upon A Time there was a language called Algol68 whose designers
appeared to be keen to get all that sort of thing absolutely right,
according to a careful reading of the "transput" specs ("I/O" was
considered an old-fashioned term).
The conclusion one had to come to was that the only way to get the
conversion of numbers between binary and decimal digit representation
right was to do all the work (not terribly quickly, to be sure) as
arbitrary length string manipulation, with only a very /very/ carefully
designed conversion to binary form, from a carefully designed canonical
string representation, as the last stage of a potentially long and
complex sequence of operations.
I've never seen anyone go to remotely as much trouble to get this stuff
right since then. I can't, however, see such an approach having a
problem with the example above.
--
Tim Ward
