[Numpy-discussion] dot() performance depends on data?

[Matthieu Brucher]

Denormal numbers are a tricky beast. You may have to change the clip
or the shift depending on the processor you have.
It's no wonder that processors and thus compilers have options to
round denormals to zero.

Matthieu

2010/9/11 Hagen Fürstenau <hagen at zhuliguan.net>:
>> Anyway, seems it is indeed a denormal issue, as adding a small (1e-10)
>> constant gives same speed for both timings.
>
> With adding 1e-10 or clipping to 0 at 1e-150, I still get a slowdown of
> about 30% compared with the random arrays. Any explanation for that?
>
> Cheers,
> Hagen
>
>
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