[pythran] Re: question on slice.hpp
- From: Neal Becker <ndbecker2@xxxxxxxxx>
- To: pythran@xxxxxxxxxxxxx
- Date: Thu, 4 Sep 2014 14:58:27 -0400
I think it is probably faster, avoiding int <-> float conversions, and
potentially more accurate.
On Thu, Sep 4, 2014 at 2:56 PM, Pierrick Brunet <pierrick.brunet@xxxxxxxx>
wrote:
> I think it is rounded up as the slice : 1:5:3 is 2 with a roundup and 1
> with a round down with your expression.
>
> It looks like your formule have the same final behavior but need more
> operation to perform it. Do you have any example where the current function
> fail?
>
>
>
> On 04/09/2014 20:32, Neal Becker wrote:
>
> In pythran/pythonic/types/slice.hpp
>
> long size() const
> {
> assert( not upper.is_none and not lower.is_none and not
> step.is_none );
> return std::max(0L, long(ceil(double(upper -
> lower)/double(step))));
> }
>
> Maybe this should be:
> (using python code here:)
>
> def roundup_divide (a, b):
> return (a + b - 1) // b
>
> return std::max(0L, roundup_divide (upper-lower, step));
>
> But on the other hand, did you really mean to roundup? Should the size
> of a slice be rounded down?
>
> --
> *Those who don't understand recursion are doomed to repeat it*
>
>
>
--
*Those who don't understand recursion are doomed to repeat it*
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