[Numpy-discussion] Scipy dot

Nicolas SCHEFFER scheffer.nicolas at gmail.com
Thu Nov 8 15:06:04 EST 2012


I've made the necessary changes to get the proper order for the output array.
Also, a pass of pep8 and some tests (fixmes are in failing tests)
http://pastebin.com/M8TfbURi

-n

On Thu, Nov 8, 2012 at 11:38 AM, Nicolas SCHEFFER
<scheffer.nicolas at gmail.com> wrote:
> Thanks for all the responses folks. This is indeed a nice problem to solve.
>
> Few points:
> I. Change the order from 'F' to 'C': I'll look into it.
> II. Integration with scipy / numpy: opinions are diverging here.
> Let's wait a bit to get more responses on what people think.
> One thing though: I'd need the same functionality as get_blas_funcs in numpy.
> Since numpy does not require lapack, what functions can I get?
> III. Complex arrays
> I unfortunately don't have enough knowledge here. If someone could
> propose a fix, that'd be great.
> IV. C
> Writing this in C sounds like a good idea. I'm not sure I'd be the
> right person to this though.
> V. Patch in numpy
> I'd love to do that and learn to do it as a byproduct.
> Let's make sure we agree this can go in numpy first and that all FIXME
> can be fixed.
> Although I guess we can resolve fixmes using git.
>
> Let me know how you'd like to proceed,
>
> Thanks!
>
> FIXMEs:
> - Fix for ndim != 2
> - Fix for dtype == np.complex*
> - Fix order of output array
>
> On Thu, Nov 8, 2012 at 9:42 AM, Frédéric Bastien <nouiz at nouiz.org> wrote:
>> Hi,
>>
>> I also think it should go into numpy.dot and that the output order should
>> not be changed.
>>
>> A new point, what about the additional overhead for small ndarray? To remove
>> this, I would suggest to put this code into the C function that do the
>> actual work (at least, from memory it is a c function, not a python one).
>>
>> HTH
>>
>> Fred
>>
>>
>>
>> On Thu, Nov 8, 2012 at 12:29 PM, Anthony Scopatz <scopatz at gmail.com> wrote:
>>>
>>> On Thu, Nov 8, 2012 at 7:06 AM, David Cournapeau <cournape at gmail.com>
>>> wrote:
>>>>
>>>> On Thu, Nov 8, 2012 at 12:12 PM, Dag Sverre Seljebotn
>>>> <d.s.seljebotn at astro.uio.no> wrote:
>>>> > On 11/08/2012 01:07 PM, Gael Varoquaux wrote:
>>>> >> On Thu, Nov 08, 2012 at 11:28:21AM +0000, Nathaniel Smith wrote:
>>>> >>> I think everyone would be very happy to see numpy.dot modified to do
>>>> >>> this automatically. But adding a scipy.dot IMHO would be fixing
>>>> >>> things
>>>> >>> in the wrong place and just create extra confusion.
>>>> >>
>>>> >> I am not sure I agree: numpy is often compiled without lapack support,
>>>> >> as
>>>> >> it is not necessary. On the other hand scipy is always compiled with
>>>> >> lapack. Thus this makes more sens in scipy.
>>>> >
>>>> > Well, numpy.dot already contains multiple fallback cases for when it is
>>>> > compiled with BLAS and not. So I'm +1 on just making this an
>>>> > improvement
>>>> > on numpy.dot. I don't think there's a time when you would not want to
>>>> > use this (provided the output order issue is fixed), and it doesn't
>>>> > make
>>>> > sense to not have old codes take advantage of the speed improvement.
>>>>
>>>> Indeed, there is no reason not to make this available in NumPy.
>>>>
>>>> Nicolas, can you prepare a patch for numpy ?
>>>
>>>
>>> +1, I agree, this should be a fix in numpy, not scipy.
>>>
>>> Be Well
>>> Anthony
>>>
>>>>
>>>>
>>>> David
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>>>
>>>
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>>
>>
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