[Numpy-discussion] advanced indexing bug with huge arrays?

Sturla Molden sturla at molden.no
Tue Jan 24 03:37:26 EST 2012

On 24.01.2012 09:21, Sturla Molden wrote:

> randomkit.c handles C long correctly, I think. There are different codes
> for 32 and 64 bit C long, and buffer sizes are size_t.

distributions.c take C longs as parameters e.g. for the binomial 
distribution. mtrand.pyx correctly handles this, but it can give an 
unexpected overflow error on 64-bit Windows:

In [1]: np.random.binomial(2**31, .5)
OverflowError                             Traceback (most recent call last)
C:\Windows\system32\<ipython-input-1-000aa0626c42> in <module>()
----> 1 np.random.binomial(2**31, .5)

C:\Python27\lib\site-packages\numpy\random\mtrand.pyd in 
mtrand.RandomState.binomial (numpy\random\mtrand\mtrand.c:13770)()

OverflowError: Python int too large to convert to C long

On systems where C longs are 64 bit, this is likely not to produce an 

This begs the question if also randomkit.c and districutions.c should be 
changed to use npy_intp for consistency across all platforms.

(I assume we are not supporting 16 bit NumPy, in which case we will need 
C long there...)


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