[Numpy-discussion] dtype promotion

[Eelco Hoogendoorn]

The tuple gets cast to an ndarray; which invokes a different codepath than
the scalar addition.

Somehow, numpy has gotten more aggressive at upcasting to float64 as of
1.8, but I havnt been able to discover the logic behind it either.


On Mon, Mar 3, 2014 at 10:06 PM, Nicolas Rougier
<Nicolas.Rougier at inria.fr>wrote:

>
> Hi all,
>
> I'm using numpy 1.8.0 (osx 10.9, python 2.7.6) and I can't understand
> dtype promotion in the following case:
>
> >>> Z = np.zeros((2,2),dtype=np.float32) + 1
> >>> print Z.dtype
> float32
>
> >>> Z = np.zeros((2,2),dtype=np.float32) + (1,1)
> >>> print Z.dtype
> float64
>
>
> Is this the expected behavior ?
> What it the difference between the two lines ?
>
>
>
> Nicolas
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