[squeak-dev] Re: [ANN] Number comparison, hash, NaN, Point, and
other partially ordered sets
schwa at fastmail.us
Sat Jan 10 10:01:03 UTC 2009
Tim Olson wrote:
> On Jan 8, 2009, at 9:30 AM, Hans-Martin Mosner wrote:
>> AFAIK, the Croquet project needs to have exactly reproducible float
>> arithmetics on all platforms.
Slightly off-topic, but since we have such a knowledgeable crowd...
As noted by John, Croquet uses fdlibm for bit-identical floating point
math. Does anyone have a feeling for how difficult (or impossible) it
will be to achieve identical computation on OpenCL-compliant devices?
For example, how difficult would it be to port, say, fdlibm, so that
trancedentals use the exact same code? Any other show-stoppers that
might not occur to the naive mind :-) ?
> Are you using the exact same code on all platforms for trancendentals
> and other floating-point functions? If not, that is going to be the
> greatest source of different results. They tend to vary widely on
> accuracy, since there is no 1/2 ULP accuracy requirement for those
> functions, unlike for the defined IEEE operations (+,-,*,/,sqrt)
> -- Tim Olson
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