[Numpy-discussion] matrix default to column vector?

Christopher Barker Chris.Barker at noaa.gov
Mon Jun 8 12:55:09 EDT 2009

Olivier Verdier wrote:
>  One 
> should realize that allowing dot(A,B,C) is just *better* than the 
> present situation where the user is forced into writing dot(dot(A,B),C) 
> or dot(A,dot(B,C)).

I'm lost now -- how is this better in any significant way?

Tom K. wrote:
> But,
> almost all experienced users drift away from matrix toward array as they
> find the matrix class too limiting or strange

That's one reason, and the other is that when you are doing real work, 
it is very rare for the linear algebra portion to be significant. I know 
in my code (and this was true when I was using MATLAB too), I may have 
100 lines of code, and one of them is a linear algebra expression that 
could be expressed nicely with matrices and infix operators. Given that 
the rest of the code is more natural with nd-arrays, why the heck would 
I want to use matrices? this drove me crazy with MATLAB -- I hated the 
default matrix operators, I was always typing ".*", etc.

 > - it seems only applicable for new users and pedagogical purposes.

and I'd take the new users of this list -- it serves no one to teach 
people something first, then tell them to abandon it. Which leaves the 
pedagogical purposes. In that case, you really need operators, slightly 
cleaner syntax that isn't infix really doesn't solve the pedagogical 

It seems there is a small but significant group of folks on this list 
that want matrices for that reason. That group needs to settle on a 
solution, and then implement it. Personally, I think the row-vector, 
column-vector approach is the way to go -- even though, yes, these are 
matrices that happen to have one dimension or the other set to one, I 
know that when I was learning LA (and still), I thought about row and 
column vectors a fair bit, and indexing them in a simple way would be 
nice.  But I don't teach, so I'll stop there.


Christopher Barker, Ph.D.

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