[Numpy-discussion] Really strange result

Charles R Harris charlesr.harris@gmail....
Fri May 1 20:40:21 CDT 2009


On Fri, May 1, 2009 at 7:39 PM, Charles R Harris
<charlesr.harris@gmail.com>wrote:

>
>
> On Fri, May 1, 2009 at 7:24 PM, Neal Becker <ndbecker2@gmail.com> wrote:
>
>> Charles R Harris wrote:
>>
>> > On Fri, May 1, 2009 at 1:02 PM, Neal Becker <ndbecker2@gmail.com>
>> wrote:
>> >
>> >> In [16]: (np.linspace (0, len (x)-1, len(x)).astype
>> (np.uint64)*2).dtype
>> >> Out[16]: dtype('uint64')
>> >>
>> >> In [17]: (np.linspace (0, len (x)-1, len(x)).astype
>> (np.uint64)*n).dtype
>> >> Out[17]: dtype('float64')
>> >>
>> >> In [18]: type(n)
>> >> Out[18]: <type 'int'>
>> >>
>> >> Now that's just strange.  What's going on?
>> >>
>> >>
>> > The  n is signed, uint64 is unsigned. So a signed type that can hold
>> > uint64 is needed. There ain't no such integer, so float64 is used. I
>> think
>> > the logic here is a bit goofy myself since float64 doesn't have the
>> needed
>> > 64 bit precision and the conversion from int kind to float kind is
>> > confusing. I think it would be better to raise a NotAvailable error or
>> > some such. Lest you think this is an isolated oddity, sometimes numeric
>> > arrays can be converted to object arrays.
>> >
>> > Chuck
>>
>> I don't think that any type of integer arithmetic should ever be
>> automatically promoted to float.
>>
>> Besides that, what about the first example?  There, I used '2' rather than
>> 'n'.  Is not '2' also an int?
>
>
> What version of numpy are you using?
>

And what is the value of n?

Chuck
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