[Numpy-discussion] GSoC?

Pauli Virtanen pav at iki.fi
Fri Mar 4 16:20:44 EST 2016


Thu, 11 Feb 2016 00:02:52 +0100, Ralf Gommers kirjoitti:
[clip]
> OK first version:
> https://github.com/scipy/scipy/wiki/GSoC-2016-project-ideas I kept some
> of the ideas from last year, but removed all potential mentors as the
> same people may not be available this year - please re-add yourselves
> where needed.
> 
> And to everyone who has a good idea, and preferably is willing to mentor
> for that idea: please add it to that page.

I probably don't have bandwidth for mentoring, but as the Numpy 
suggestions seem to be mostly "hard" problems, we can add another 
one:

## Dealing with overlapping input/output data

Numpy operations where output arrays overlap with 
input arrays can produce unexpected results.
A simple example is
```
x = np.arange(100*100).reshape(100,100)
x += x.T        # <- undefined result!
```
The task is to change Numpy so that the results
here become similar to as if the input arrays
overlapping with output were separate (here: `x += x.T.copy()`).
The challenge here lies in doing this without sacrificing 
too much performance or memory efficiency.

Initial steps toward solving this problem were taken in
https://github.com/numpy/numpy/pull/6166
where a simplest available algorithm for detecting
if arrays overlap was added. However, this is not yet
utilized in ufuncs. An initial attempt to sketch what 
should be done is at https://github.com/numpy/numpy/issues/6272
and issues referenced therein.




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