Re: [eigen] Decrease in performances

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On 25.06.2012 16:36, Maxime REIS wrote:

Everything is fine up to the fix of 'Bug 363' :
- 4281:25ba289d5292 runs fast
- 4282:a07628375b86 doesn't compile
- 4283:f76f77b7d086 is sloooooooow
The bug fix apparently slowed down the whole thing, and the perfs were
improved again in c29d777b278c (some 40 or so commits after the decrease),
but not to the point they were before the bug fix.
I guess it's the price to pay to have a robust library. From that point on,
all subsequent commits don't seem to affect overall performances (at least
from my observations)

I don't know if it deserves further investigation...

It seems the performance loss is due to the integer division which checks for overflow. I guess it can easily be replaced by 128bit integer multiplication. I suggested that back then, but I guess it was ignored due to portability concerns:


Dipl.-Inf. Christoph Hertzberg
Cartesium 0.049
Universität Bremen
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