[Numpy-discussion] matrix problem: float to matrix power

Timothy Hochberg tim.hochberg@ieee....
Thu Nov 1 14:41:42 CDT 2007


On Nov 1, 2007 12:20 PM, Alan G Isaac <aisaac@american.edu> wrote:

> On Wed, 31 Oct 2007, Timothy Hochberg apparently wrote:
> > because M**n results in the matrix power of n. It would be
> > confusing if n**M did a broadcast element wise power.
>
>
>
> In an attempt to summarize:
> scalar to a matrix power
>
> 1. may have been overlooked, or may have been omitted as
> confusing
> 2. if overlooked there are two possible answers as to what
> it could reasonably be
>        a. a**m = exp(ln(a)*m)          natural definition


For some definition of natural: it makes sense once you see it, but is seem
like most people expected something else (in our four person sample, only
one person came up with this definition -- not that that's good
statistics.).


>
>        b. a**m = a**m.A                broadcasting
>
> In languages that provide an answer, I have the impression
> that the answer is usually (b).  (E.g., GAUSS.)  However
> perhaps in NumPy this is the least interesting way to go?
> But it is what I was expecting.


I'd  inclined to leave it unimplemented. It seems like it's likely to cause
confusion and my impression is that it's not a common enough construction
that having to use a function should be a big burden for most if not all
people.


-- 
.  __
.   |-\
.
.  tim.hochberg@ieee.org
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