[Numpy-discussion] (Late) summary of PEP-225 discussion at Scipy

Eric Firing efiring@hawaii....
Wed Oct 29 14:33:03 CDT 2008


David Warde-Farley wrote:
> Hi Fernando,
> 
> In Robert's comment, I think the reST processor somehow got rid of a  
> backslash. In my browser I see
> 
> 	(I'm looking at you, Matlab's "")
> 
> although this is an aside that will be lost on anyone who hasn't used  
> the Matlab backslash operator anyway.
> 
> In fact, one other thing just came to mind that isn't obvious and (so  
> far as I can remember) hasn't been brought up: even though Robert and  
> others (myself included) really only care about an operator to  
> facilitate matrix multiplication, I think most of us would support the  
> ~*=  (mentioned in the PEP) as a natural companion to ~*.

This makes no sense to me at all.  Why use in-place notation for an 
operation that is not in-place?  The point of having a matrix 
multiplication operator is to facilitate code that corresponds more 
closely to mathematical notation.  The in-place operations live in the 
computer science world, not the mathematical world.  The proposal for 
~*= violates language consistency while doing nothing to improve 
mathematical readability.

Eric

> 
> Am I right about this? I realize it can't buy you the same in-place  
> semantics as +-= and friends currently enjoy with numpy arrays, but I  
> think most folks would just *expect* it to work,  i.e. if foo is 3x4  
> and bar is 4x1 (or maybe a length 4 rank 1 array) then
> 
> 	foo ~*= bar
> 
> results in foo now pointing to an array that (however you choose to  
> handle rank) contains exactly 3 elements.
> 
> 
> Cheers,
> 
> David
> 
> 
> On 29-Oct-08, at 2:50 AM, Fernando Perez wrote:
> 
>> On Mon, Oct 27, 2008 at 12:27 PM, Fernando Perez  
>> <fperez.net@gmail.com> wrote:
>>
>>> I just got back from some travel and will try to update the doc later
>>> this evening with all the feedback and will post again, so that we  
>>> can
>>> converge on a final doc, which I'll then pitch over the fence to the
>>> python-dev list.
>> OK, thanks everyone for the feedback.  I've updated the bzr repo in
>> case anyone is using that, as well as the static copy:
>>
>> https://cirl.berkeley.edu/fperez/static/numpy-pep225/
>>
>> Please have a look (the html is in sync with the source reST doc) and
>> let me know if you have any more feedback, changes, etc.  I've tried
>> to put in all of your comments and suggestions, but please say so  if
>> I've missed something or you feel anything not to be accurate.
>>
>> I'll leave it for a few days up, and if there are no objections by
>> next week, I'll  send it to the Python-dev list.  That will give them
>> some days to think about it, in case anyone from that  list is
>> interested in talking about it at the Nov 13 baypiggies meeting.
>>
>> Cheers,
>>
>> f
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