At 4/13/01 03:42 AM, Peter Holm wrote:
>mysql> select floor(23.49999999999999 + 0.5);
>+--------------------------------+
>| floor(23.49999999999999 + 0.5) |
>+--------------------------------+
>| 23 |
>+--------------------------------+
>
>mysql> select floor(23.499999999999999 + 0.5);
>+---------------------------------+
>| floor(23.499999999999999 + 0.5) |
>+---------------------------------+
>| 24 |
>+---------------------------------+
>
>Why are there different results?
Apparently the closest (most accurate) expression of the first constant
(23.49999999999999) as a floating point number using binary arithmetic is
less than 23.5 while the closest expression of the second constant
(23.499999999999999) is 23.5 or greater. For some insight into why this
happens, try to write 0.1 as the sum of reciprocal powers of 2 ( as in 1/16
+ 1/32 + ... ).
--
Dennis Nichols
[EMAIL PROTECTED]
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