[Numpy-discussion] Matlab page on scipy wiki

Bill Baxter wbaxter at gmail.com
Thu Feb 9 16:19:24 CST 2006


I find 'number of axes' to be even more confusing than 'dimension'.  Both
sound to me like they're talking about the number of components in a vector
(e.g. 3-dimensional space vs 2-dimensional space), but axes moreso.  The
word dimension has a lot of uses, and in most programming languages arrays
are described as being one, two or three dimensional etc.  So that makes
sense.  But I can't think of any common usages of axis that aren't related
to vectors in a vector space.

But that's just me.  Seems like this debate probably came and went a long
time ago.  What is right probably depends mostly on what sort of math you
spend your time doing.

--bb

On 2/10/06, Sasha <ndarray at mac.com> wrote:
>
> On 2/9/06, Alan G Isaac <aisaac at american.edu> wrote:
> > Unfortunately the SciPy book currently uses the term 'rank'
> > in the two conflicting ways.  (It uses 'rank' in the linear
> > algebra sense only in the discussion of lstsq on p.145.)
> > It might be helpful for the tensor sense to always be
> > qualified as 'tensor rank'?
>
> Another alternative would be "number of axes."   I also find a
> glossary used by the J language (an APL descendant) useful in array
> discussions. See
> <http://www.jsoftware.com/books/help/jforc/glossary.htm >.
>
> Here is how J documentation explains the difference in their
> terminology and that of the C language: "What C calls an n-dimensional
> array of rank i×j×…×k is in J an array of rank n with axes of length
> i,j,…,k."  <http://www.jsoftware.com/books/help/jforc/declarations.htm>
>
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