A use for integer quotients

Terry Reedy tjreedy at home.com
Mon Jul 23 08:36:50 CEST 2001


"Tim Peters" <tim.one at home.com> wrote in message
news:mailman.995866298.23496.python-list at python.org...
> I've mentioned before that the best way to compute int ceiling in
Python is
> via:
>
>     def ceiling_of_quotient(i, j):
>         q, r = divmod(i, j)
>         return q + (r != 0)
>
> and that code doing (i + (j-1))/j instead is flirting with
sign-related
> errors and spurious OverflowError (there's code like that in the std
> library, although in context neither sign errors nor OverflowError
should be
> possible).

The first line of the my partition algorithm is
if 1 <= k <= n: raise ValueError
so sign-related error is not possible where I used this.  Spurious
overflow is possible, though only with n,k large enough to make
computation impractical anyway.  General point is good to keep in mind
though.






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