[Python-ideas] Python-ideas Digest, Vol 88, Issue 199

[Colin J. Williams]

#4 seems to refer to the Python basic system.

However numpy.array does deal with multi-dimension arrays.
On 23-Mar-2014 9:08 PM, python-ideas-request at python.org wrote:
> ------------------------------ Message: 4 Date: Mon, 24 Mar 2014 
> 11:49:43 +1100 From: Steven D'Aprano <steve at pearwood.info> To: 
> python-ideas at python.org Subject: Re: [Python-ideas] [RFC] draft PEP: 
> Dedicated infix operators for matrix multiplication and matrix power 
> Message-ID: <20140324004943.GX16526 at ando> Content-Type: text/plain; 
> charset=us-ascii On Sun, Mar 23, 2014 at 11:40:10AM +0100, Sturla 
> Molden wrote:
>> On 15/03/14 01:09, Antoine Pitrou wrote:
>>
>>> Really? That should be up to the third-party library implementing the @
>>> operator for its types, not to the language itself: Python _suggests_
>>> an use case for @, it doesn't mandate it (especially as there's no
>>> appropriate data type in the stdlib).
>> array.array is an appropriate type for supporting @ for matrix
>> multiplication.
> No it isn't. The PEP even discusses it:
>
>
>      [quote]
>      array objects cannot represent multidimensional data at all,
>      which makes ``__matmul__`` much less useful.  Second,
>      providing a quality implementation of matrix multiplication
>      is highly non-trivial.  Naive nested loop implementations
>      are very slow and providing one in CPython would just create
>      a trap for users.  But the alternative -- providing a modern,
>      competitive matrix multiply -- would require that CPython link
>      to a BLAS library, which brings a set of new complications.
>      In particular, several popular BLAS libraries (including the
>      one that ships by default on OS X) currently break the use of
>      ``multiprocessing`` [#blas-fork]_.  And finally, we'd have to
>      add quite a bit beyond ``__matmul__`` before ``memoryview``
>      or  ``array.array`` would be useful for numeric work -- like
>      elementwise versions of the other arithmetic operators, just
>      to start.
>      [end quote]
>
>
>

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