[Numpy-discussion] matrix multiply

Charles R Harris charlesr.harris at gmail.com
Sun Apr 6 23:34:48 EDT 2008


On Sun, Apr 6, 2008 at 8:51 PM, Alan G Isaac <aisaac at american.edu> wrote:

> On Sun, 6 Apr 2008, Charles R Harris apparently wrote:
> > I prefer the modern usage myself as it is closer to the
> > accepted logic operations, but applying algebraic
> > manipulations like powers and matrix inverses in that
> > context leads to strange results.
>
> I have not really thought much about inverses,
> but nonnegative integer powers have a natural
> interpretation in graph theory (with the boolean
> algebra operations, not the boolean ring operations).
> This is exactly what I was requesting be preserved.
>

You mean as edges in a directed graph? I suppose so, although graph
algorithms tend to use different structures, lists of lists, trees, and
such. I would think plain old integer matrices might actually carry more
information; let me count the ways. And positive matrices have their own
oddities. Hmm... I wonder what matrices over Z_2 mean in that context?

Chuck
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