[Numpy-discussion] Speeding up numarray -- questions on its design

Perry Greenfield perry at stsci.edu
Wed Jan 19 08:45:32 CST 2005


Konrad Hinsen wrote:

>> comment, I could easily have missed where that support is provided.  
>> I'm mainly following up on Konrad's comment that his Automatic 
>> differentiation does not work with Numarray because of the missing 
>> support for object arrays.  There are other applications for object 
>> arrays as well.   Most of the
>
> While I agree that object arrays are useful, they have nothing to do 
> with the missing feature that I mentioned recently. That one concerns 
> only ufuncs. In NumPy, they use a method call when presented with an 
> object type they cannot handle directly. In numarray, they just 
> produce an error message in that case.
>
> Returning to object arrays, I have used them occasionally but never in 
> any of my public code, because there have been lots of minor bugs 
> concerning them in all versions of NumPy. It would be nice if numarray 
> could do a better job there.
>
This is a good point. In fact, when we started thinking about 
implementing object arrays, it looked tricker than it first appeared. 
One needs to ensure that all the objects referenced in the arrays have 
their reference counts appropriately adjusted with all operations. At 
that time it was quite easy to segfault Numeric using object arrays I'm 
guessing for this reason. Perhaps those problems have since been fixed. 
I don't recall the exact manipulations that caused the segfaults, but 
they were simple operations; and I don't know if the same problems 
remain.

Perry





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