Negativ nearest interger?

Jussi Piitulainen jpiitula at ling.helsinki.fi
Thu Sep 22 13:44:15 CEST 2011


joni writes:

> Have a simple question in the Integer calculator in Python 2.65 and
> also 2.7..
> 
> The consol showing:
> 
> Python 2.6.5 (r265:79063, Apr 16 2010, 13:09:56)
...
> >>> -7/3
> -3
> >>>
> 
> -3 are more wrong than -2. Negativ number seems not to round to
> nearest interger, but the integer UNDER the anwser!! Or?
> 
> Why?

It simply does not round to the nearest integer. It floors. This has
nicer mathematical properties. In particular, it allows the remainder
(notated as "per cent") operation (n % m) to return a number that
differs from n by a multiple of m ("is congruent to n modulo m").
These two operations go together.



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