[Numpy-discussion] NumPy-Discussion Digest, Vol 90, Issue 56

[Colin J. Williams]

Julian,

I can see the need to recognize both column and row vectors, but why not 
with np.matrix?

I can see no need for a new operator and hope to be able to comment more 
fully on PEP 465 in a few days.

Colin W.
On 17-Mar-2014 7:19 PM, numpy-discussion-request at scipy.org wrote:
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>     1. Re: [help needed] associativity and precedence	of '@'
>        (Nathaniel Smith)
>     2. Re: GSoC project: draft of proposal (Julian Taylor)
>     3. Re: [help needed] associativity and precedence	of '@'
>        (Christophe Bal)
>     4. Re: [help needed] associativity and precedence	of '@'
>        (Alexander Belopolsky)
>     5. Re: [help needed] associativity and precedence	of '@' (Bago)
>     6. Re: [help needed] associativity and precedence	of '@'
>        (Christophe Bal)
>     7. Re: [help needed] associativity and precedence	of '@'
>        (Christophe Bal)
>     8. Re: [help needed] associativity and precedence	of '@'
>        (Nathaniel Smith)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 17 Mar 2014 22:02:33 +0000
> From: Nathaniel Smith <njs at pobox.com>
> Subject: Re: [Numpy-discussion] [help needed] associativity and
> 	precedence	of '@'
> To: Discussion of Numerical Python <numpy-discussion at scipy.org>
> Message-ID:
> 	<CAPJVwB=zBazN+fiYWJeiWOL=4a9Bf2XGxJGoTT8GFTt-kDUDZw at mail.gmail.com>
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> On Mon, Mar 17, 2014 at 9:38 PM, Christophe Bal <projetmbc at gmail.com> wrote:
>> Here is the translation. ;-)
>>
>> Hello,
>> and what about something like that ?
>>
>> a @ b @ c  ->  (a @ b) @ c
>> a * b @ c  ->  (a * b) @ c
>> a @ b * c  ->  a @ (b * c)
>>
>> Easy to remember: the *-product has priority regarding to the @-product, and
>> we just do @-product from left to right.
> In the terminology we've been using in this thread, this is "weak-left".
>
>> An advantage of this is that most parsers do analyze from left to right.
>>
>> So I really think that it is a better choice than the weak-right one.
> We've mostly ignored this option because of assuming that if we want
> left-associativity, we should go with "same-left" instead of
> "weak-left". Same-left is:
>
> a @ b @ c -> (a @ b) @ c
> a * b @ c -> (a * b) @ c
> a @ b * c -> (a @ b) * c
>
> i.e., even more left-to-right than weak-left :-)
>
> Do you think weak-left is better than same-left?
>

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