RFR 8005311: Add Scalable Updatable Variables, DoubleAccumulator, DoubleAdder, LongAccumulator, LongAdder (original) (raw)

Joe Darcy joe.darcy at oracle.com
Sat Jan 12 02:37:51 UTC 2013

On 01/11/2013 09:18 AM, Chris Hegarty wrote:

On 11/01/2013 16:57, Doug Lea wrote:

On 01/11/13 11:35, Peter Levart wrote:

On 01/11/2013 05:18 PM, Chris Hegarty wrote:

Now with explicit disclaimer on DoubleA*

"The order of accumulation within or across threads is not guaranteed. Thus, this class may not be applicable if numerical stability is required when combining values of substantially different orders of magnitude." It doesn't have to be substantially different order of magnitude. Thanks. Chris, please add "especially":

Hello,

I would prefer to cautionary note along the lines of "if you want numerical accuracy, take care to use a summation algorithm with defined worst-case behavior."

(Varying magnitude is not so much of a problem if you add things up in the right order.)

-Joe

Thanks Doug, done. -Chris.

"The order of accumulation within or across threads is not guaranteed. Thus, this class may not be applicable if numerical stability is required, especially when combining values of substantially different orders of magnitude."

-Doug

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