[Numpy-discussion] please change mean to use dtype=float
haase at msg.ucsf.edu
Wed Sep 20 10:47:03 CDT 2006
Robert Kern wrote:
>> This was not supposed to be a scientific statement -- I'm (again)
>> thinking of our students that not always appreciate the full
>> of computational numerics and data types and such.
> They need to appreciate the complexity of computational numerics if
> they are going to do numerical computation. Double precision does not
> make it any simpler.
This is were we differ.
> We haven't forgotten what newcomers will do; to the contrary, we are
> quite aware
> that new users need consistent behavior in order to learn how to use a
> Adding another special case in how dtypes implicitly convert to one
> another will
> impede new users being able to understand the whole system.
All I'm proposing could be summarized in:
mean(), sum(), var() ... produce output of dtype float64 (except for
input float96 which produces float96)
A comment on this is also that for these operations the input
type/precision is almost not related to the resulting output precision
-- the int case makes that already clear. (This is different for e.g.
min() or max() )
The proposed alternative implementations seem to have one or more
multiplication (or division) for each value -- this might be noticeably
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