[Numpy-discussion] Possible bug: uint64 + int gives float64
Hi, I just noticed some weird behavior in operations with uint64 and int, heres an example: numpy.uint64(3)+1 4.0 type(numpy.uint64(3)+1) type 'numpy.float64' Pearu ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Possible bug: uint64 + int gives float64
int can be larger than numpy.int64 therefore it should be coerced to float64 (or float96/float128) Nadav -Original Message- From: numpy-discussion-boun...@scipy.org on behalf of Pearu Peterson Sent: Sun 13-Jun-10 12:08 To: Discussion of Numerical Python Subject: [Numpy-discussion] Possible bug: uint64 + int gives float64 Hi, I just noticed some weird behavior in operations with uint64 and int, heres an example: numpy.uint64(3)+1 4.0 type(numpy.uint64(3)+1) type 'numpy.float64' Pearu ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion winmail.dat___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Possible bug: uint64 + int gives float64
On Sun, Jun 13, 2010 at 4:45 PM, Nadav Horesh nad...@visionsense.com wrote: int can be larger than numpy.int64 therefore it should be coerced to float64 (or float96/float128) Ok, I see. The results type is defined by the types of operands, not by their values. I guess this has been discussed earlier but with small operands this feature may be unexpected. For example, with the same rule the result of int64 + int should be float64 while currently it is int64. Pearu ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Possible bug: uint64 + int gives float64
On Sun, Jun 13, 2010 at 9:20 AM, Pearu Peterson pearu.peter...@gmail.comwrote: On Sun, Jun 13, 2010 at 4:45 PM, Nadav Horesh nad...@visionsense.com wrote: int can be larger than numpy.int64 therefore it should be coerced to float64 (or float96/float128) Ok, I see. The results type is defined by the types of operands, not by their values. I guess this has been discussed earlier but with small operands this feature may be unexpected. For example, with the same rule the result of int64 + int should be float64 while currently it is int64. It's the combination of unsigned with signed that causes the promotion. The int64 type can't hold the largest values in uint64. Strictly speaking, doubles can't hold either of the 64 bit integer types without loss of precision but at least the degradation is more gradual. Another possibility here would be to raise an error/warning because no suitable integer type is available, that would be perhaps less surprising than the promotion to float. IIRC, there is also a case where numeric arrays get promoted to objects, but I don't see my old table of such things floating about at the moment. Chuck ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Possible bug: uint64 + int gives float64
Den 13.06.2010 18:19, skrev Charles R Harris: It's the combination of unsigned with signed that causes the promotion. The int64 type can't hold the largest values in uint64. Strictly speaking, doubles can't hold either of the 64 bit integer types without loss of precision but at least the degradation is more gradual. Another possibility here would be to raise an error/warning because no suitable integer type is available, that would be perhaps less surprising than the promotion to float. As I see it, the 'correct' solution would be coercion to an arbitrarily long integer, such as 'long' in Python 2 and 'int' in Python 3. Sturla ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
