A use for integer quotients

[David Eppstein]

In article <3B5C3713.A5201C5A at letterror.com>,
 Just van Rossum <just at letterror.com> wrote:

> 1) only one of the / operands need to be a float to force a float
> outcome, and 2) there is a round() builtin function. Now, if we
> initialize k to a float, we can write it like so:
> 
>    int(round(bytes/k))
> 
> I really don't see how the int examples you gave are in any way superior.

In the case under discussion it doesn't matter (the rounded number is just 
an approximation for human discussion) but it is just wrong to me to 
confuse integers and floating point numbers to the extent that you 
gratuitously convert from int to float and back when you don't need to and 
think it an improvement.  Integers are exact.  Floating point numbers are 
approximate.  Integers allow rearrangements like (a+b)+c=a+(b+c), floating 
point numbers don't.  If you need your numbers to be computed exactly, and 
your programming language turns them into floats behind your back, it will 
cause bugs.
-- 
David Eppstein       UC Irvine Dept. of Information & Computer Science
eppstein at ics.uci.edu http://www.ics.uci.edu/~eppstein/