numpy-discussion

[Numpy-discussion] log can't handle big ints

[David G. <dav...@gm...>]

I am using numpy-0.9.8 and it seems that numpy's log2 function can't
handle large integers?

In [19]: a=11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111

In [20]: math.log(a,2)
Out[20]: 292.48167544353294

In [21]: numpy.log2(a)
---------------------------------------------------------------------------
exceptions.AttributeError                            Traceback (most
recent call last)

/home/david/<ipython console>

/usr/lib/python2.4/site-packages/numpy/lib/ufunclike.py in log2(x, y)
     52     x = asarray(x)
     53     if y is None:
---> 54         y = umath.log(x)
     55     else:
     56         umath.log(x, y)

AttributeError: 'long' object has no attribute 'log'

Does anyone else get this in numpy? if not, what version are you using?

-- 
David Grant
http://www.davidgrant.ca

Re: [Numpy-discussion] log can't handle big ints

[Travis O. <oli...@ie...>]

David Grant wrote:
> I am using numpy-0.9.8 and it seems that numpy's log2 function can't
> handle large integers?
>
> In [19]: a=11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111
>
> In [20]: math.log(a,2)
> Out[20]: 292.48167544353294
>
> In [21]: numpy.log2(a)
>   

Ufuncs on objects (like the long object) work by looking for the 
corresponding method.  It's not found for long objects.

Convert the long object to a float first.   I'm not sure of any other 
way to "fix" it.  I suppose if no method is found an attempt to convert 
them to floats could be performed under the covers on all object array 
inputs.

-Travis