Changes between Version 1 and Version 3 of Ticket #10545


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Timestamp:
01/03/11 14:04:49 (2 years ago)
Author:
rbeezer
Comment:

Hi Nils,

Thanks for the comments. Since vectors are neither rows nor columns in Sage, any notion of a transpose is irrelevant. The outer product just is what it is. I could delete the mention of the transpose in the mathematical description in the docstring.

"Someone" are 19-year-old students, who shouldn't need to understand a lambda function to learn linear algebra.

Sage can work well with a column-oriented approach - it just needs a few things. Check out:

 http://wiki.sagemath.org/devel/LatexToWorksheet

 http://linear.ups.edu

Rob

Replying to nbruin:

I didn't know that is sometimes used as a definition of "outer product", but Wikipedia backs you up on it.

In other languages, "exterior product" translates to the same word as "outer product", so a -1 from me for having this definition of outer product. I think this term will be a source of confusion.

If someone needs the tensor product, it is easy enough to get via the one-liner

lambda v,w: matrix(len(v),len(w),[a*b for a in v for b in w])

(given Sage's preference for row vectors versus the preference of most LA texts for column vectors, I expect that relating inner/outer products to a question of where to put the transpose is only going to cause *more* confusion in students, by the way)

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  • Ticket #10545 – Description

    v1 v3  
    11Title pretty much says it all.  Students frequently can't tell an inner product from an outer product (probably not too careful about where a transpose is).  Maybe this will help. 
    22 
    3 Depends on #10541 
     3Depends on #10541  
    44