Sebastian Haase wrote:
The best I can hope for is a "sound" default for most (practical) cases... I still think that 80bit vs. 128bit vs 96bit is rather academic for most people ... most people seem to only use float64 and then there are some that use float32 (like us) ...
I fully agree with Sebastian here. As Travis pointed out, "all we are talking about is the default". The default should follow the principle of least surprise for the less-knowledgeable users. Personally, I try to always use doubles, unless I have a real reason not to. The recent change of default types for zeros et al. will help. clearly, there is a problem to say the default accumulator for *all* types is double, as you wouldn't want to downcast float128s, even if they are obscure. However, is it that hard to say that the default accumulator will have *at least* the precision of double? Robert Kern wrote:
Let me offer a third path: the algorithms used for .mean() and .var() are substandard. There are much better incremental algorithms that entirely avoid the need to accumulate such large (and therefore precision-losing) intermediate values.
This, of course, is an even better solution, unless there are substantial performance impacts. -Chris -- Christopher Barker, Ph.D. Oceanographer NOAA/OR&R/HAZMAT (206) 526-6959 voice 7600 Sand Point Way NE (206) 526-6329 fax Seattle, WA 98115 (206) 526-6317 main reception Chris.Barker@noaa.gov