[Numpy-discussion] uint64 typecasting with scalars broken (?)

Travis Oliphant oliphant.travis@ieee....
Mon Apr 23 20:44:20 CDT 2007


Christian Marquardt wrote:
> Hello,
>
> The following is what I expected...
>
>    >>> y = 1234
>    >>> x = array([1], dtype = "uint64")
>    >>> print x + y, (x + y).dtype.type
>    [1235] <type 'numpy.uint64'>
>
>   

This is "what you expect" only because y is a scalar and cannot 
determine the "kind" of the output.

> but is this the way it should be? (numpy 1.0.2, Linux, Intel comilers)
>
>    >>> print x[0] + y, type(x[0] + y)
>    1235.0 <type 'numpy.float64'>
>   

This is correct (sort of) because in a mixed operation between uint64 
and int32, because there is no int128, the sum must be placed in a 
float.  In reality it should be a long-double float but it was decided 
not to perpetuate long double floats like this because then on 64-bit 
platforms they would be showing up everywhere.

-Travis



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