[Numpy-discussion] please change mean to use dtype=float

[Travis Oliphant]

David M. Cooke wrote:

>
>Conclusions:
>
>- If you're going to calculate everything in single precision, use Kahan
>summation. Using it in double-precision also helps.
>- If you can use a double-precision accumulator, it's much better than any of
>the techniques in single-precision only.
>
>- for speed+precision in the variance, either use Kahan summation in single
>precision with the two-pass method, or use double precision with simple
>summation with the two-pass method. Knuth buys you nothing, except slower
>code :-)
>
>After 1.0 is out, we should look at doing one of the above.
>  
>

+1