Sebastian Haase wrote:

>On Tuesday 19 September 2006 15:48, Travis Oliphant wrote:
>
>
>>Sebastian Haase wrote:
>>
>>
><snip>
>
>
>>>can we please change dtype to default to float64 !?
>>>
>>>
>>The default is float64 now (as long as you are not using
>>numpy.oldnumeric).
>>
>>I suppose more appropriately, we could reduce over float for integer
>>data-types when calculating the mean as well (since a floating point is
>>returned anyway).
>>
>>
>>
>
>Is now mean() always "reducing over" float64 ?
>The svn note """Log:
>Fix mean, std, and var methods so that they reduce over double data-type with
>integer inputs.
>"""
>makes it sound that a float32 input is stays float32 ?
>
>
Yes, that is true.  Only integer inputs are changed because you are
going to get a floating point output anyway.

>For mean calculation this might introduce large errors - I usually would
>require double-precision for *any*  input type ...
>
>
Of course.  The system is not fool-proof.  I hesitate to arbitrarily
change this.  The advantage of using single-precision calculation is
that it is faster.  We do rely on the user who expressly requests these
things to be aware of the difficulties.