MFC's 754-2008 errata list: floor()

[Michel Hack <hack@xxxxxxxxxxxxxx>]

Fred Tydeman had complained that the floor() function had been used
in the definition of the value of logB() and the preferred exponent
for squareRoot().  One of the suggested fixes was "or it could be
added to the list of recommended functions".

That fix is not applicable, as 754-2008 has nothing to say about
functions from Integers to Integers.  Two related operations exist
already:  convertToIntegerTowardNegative()
and       roundToIntegralTowardNegative().

In my opinion "floor()" was simply being used in its mathematical
sense, just as "addition" and "multiplication" are.  One could
mention that the ...TowardNegative() operations effectively implement
the mathematical floor() function, and also mention ceiling() in that
context.

(The first suggestion was simply to add the definition of floor()
as explanatory text in 5.3.3 and 5.4.1 (with the latter presumably
referring back to 5.3.3).  I'm not sure it is needed, but it would
not hurt, especially as we must be careful to ensure that it is not
misinterpreted as "truncate towards zero".)

Michel.
---Sent: 2009-04-02 15:06:24 UTC