Re: [Numpy-discussion] Strange Error with NumPy Addendum
On Fri, Aug 7, 2009 at 07:15, Nanime Puloskinpulo...@gmail.com wrote: But if it were an unsigned int64, it should be able to hold 2**64 or at least 2**64-1. Am I correct? There is no numpy.sin() implementation for uint64s, just the floating point types. -- Robert Kern I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth. -- Umberto Eco ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Strange Error with NumPy Addendum
But if it were an unsigned int64, it should be able to hold 2**64 or at least 2**64-1. Am I correct? On Fri, Aug 7, 2009 at 1:03 AM, David Warde-Farley d...@cs.toronto.eduwrote: On 6-Aug-09, at 7:29 PM, Robert Kern wrote: For that value, yes, but not for long objects in general. We don't look at the value itself, just the type. Err, don't look at the value (of a long), except when it's representable with an integer dtype, right? Hence why 2**63 - 1 works. David ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
[Numpy-discussion] Strange Error with NumPy
Can anyone explain to me why I receive an error(AtrributeError) in NumPy when I do numpy.sin(2**64), but not when I do numpy.sin(2.0**64), numpy.sin(float(2**64)) or even numpy.sin(2)? Where is the root problem in all of this? ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Strange Error with NumPy
On Thu, Aug 6, 2009 at 17:01, Nanime Puloskinpulo...@gmail.com wrote: Can anyone explain to me why I receive an error(AtrributeError) in NumPy when I do numpy.sin(2**64), but not when I do numpy.sin(2.0**64), numpy.sin(float(2**64)) or even numpy.sin(2)? Where is the root problem in all of this? numpy deals with objects that can be natively represented by the C numerical types on your machine. On your machine 2**64 gives you a Python long object which cannot be converted to one of the native C numerical types, so numpy.sin() treats it as a regular Python object. The default implementation of all of the ufuncs when faced with a Python object it doesn't know about is to look for a method on the object of the same name. long.sin() does not exist, so you get an AttributeError. -- Robert Kern I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth. -- Umberto Eco ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Strange Error with NumPy
On 6-Aug-09, at 6:01 PM, Nanime Puloski wrote: Can anyone explain to me why I receive an error(AtrributeError) in NumPy when I do numpy.sin(2**64), but not when I do numpy.sin(2.0**64), numpy.sin(float(2**64)) or even numpy.sin(2)? In [6]: type(2**64) Out[6]: type 'long' In [7]: type(2) Out[7]: type 'int' In [8]: type(2.0**64) Out[8]: type 'float' Probably because 2**64 yields a long, which is an arbitrary precision type in Python, and numpy is having trouble casting it to something it can use (it's too big for numpy.int64). Notice that np.sin(2**63 - 1) works fine while np.sin(2**63) doesn't - 2**63 - 1 is the largest value that an int64 can hold. You're right that it could be approximately represented as a float32 or float64, but numpy won't cast from exact types to inexact types without you telling it to do so. I agree that the error message is less than ideal. David ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
[Numpy-discussion] Strange Error with NumPy Addendum
Thank you for your responses so far. What I also do not understand is why sin(2**64) works with the standard Python math module, but fails to do so with NumPy? To Robert Kern: Can't 2^64 be represented in C as a long double? It seems to work well on my machine. ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Strange Error with NumPy Addendum
On Thu, Aug 6, 2009 at 18:26, Nanime Puloskinpulo...@gmail.com wrote: Thank you for your responses so far. What I also do not understand is why sin(2**64) works with the standard Python math module, but fails to do so with NumPy? math.sin() always converts the argument to a float. We do not. To Robert Kern: Can't 2^64 be represented in C as a long double? For that value, yes, but not for long objects in general. We don't look at the value itself, just the type. -- Robert Kern I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth. -- Umberto Eco ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Strange Error with NumPy Addendum
On 6-Aug-09, at 7:29 PM, Robert Kern wrote: For that value, yes, but not for long objects in general. We don't look at the value itself, just the type. Err, don't look at the value (of a long), except when it's representable with an integer dtype, right? Hence why 2**63 - 1 works. David ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Strange Error with NumPy Addendum
On Fri, Aug 7, 2009 at 00:03, David Warde-Farleyd...@cs.toronto.edu wrote: On 6-Aug-09, at 7:29 PM, Robert Kern wrote: For that value, yes, but not for long objects in general. We don't look at the value itself, just the type. Err, don't look at the value (of a long), except when it's representable with an integer dtype, right? Hence why 2**63 - 1 works. Err, you may be right. -- Robert Kern I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth. -- Umberto Eco ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
