[Numpy-discussion] still no cross product for new array type

Chris Barker Chris.Barker at noaa.gov
Mon Aug 15 12:56:34 CDT 2005


Gary Ruben wrote:
> "Usually" means that that's where they are now, because they haven't 
> been implemented in numpy. Comparing with Matlab/IDL where their status 
> is slightly greater so as to earn operations of their own, I wonder why 
> equivalent status isn't afforded them in numpy.

Because numpy is NOT matlab or IDL, nor is it trying to be a close of 
either of them.

I've never used IDL, but MATLAB is (or at least was) a MATrix 
LABoratory. It was conceived, from the beginning, to be a tool to do 
linear algebra computations.

The new array type has nothing to do with linear algebra, nor does 
Numeric or numarray. they are general purpose array packages. As it 
happens, a handy way to store matrices is in a 2-d array, so it's 
natural to build a linear algebra (and vector arithmetic) package on top 
of NumPy arrays, but it should be higher level package.

One of the things I like most about NumPY, as opposed to MATLAB, is that 
it doesn't assume everything is a matrix!

If we could ever get Python to include additional operators, we could 
have a Numeric array package and linear algebra package all in one.. 
both with nice notation, that would be nice.

In the meantime, check out cvxopt:

http://www.ee.ucla.edu/~vandenbe/cvxopt/

If you want a matrix package. The author is talking about using the new 
array specification in future versions.

-Chris

-- 
Christopher Barker, Ph.D.
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Chris.Barker at noaa.gov




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