Coolest Python recipe of all time

[Raymond Hettinger]

On May 2, 11:23 pm, Stefan Behnel <stefan... at behnel.de> wrote:
> Terry Reedy, 03.05.2011 08:00:
>
> > On 5/3/2011 1:04 AM, Stefan Behnel wrote:
>
> >> The bad thing about this recipe is that it requires quite a bit of
> >> background knowledge in order to infer that the code the developer is
> >> looking at is actually correct.
>
> > The main math knowledge needed is the trivial fact that if a*x + b = 0,
> > then x = -b/a. The other math knowledge needed is that complex numbers add
> > componentwise. The trick is that replacing x with j and evaluating
> > therefore causes (in Python) all the coefficients of x (now j) to be added
> > together separately from all the constant terms to reduce the linear
> > equation to a*x+b (= 0 implied).
>
> As your above paragraph proves, it's the kind of implementation that
> requires three lines of executing code and at least 6 lines of additional
> comment. Hopefully accompanied by an excuse of the developer.

If you found nothing educational, interesting, or amusing about the
three-line linear equation solver, then you're *really* going to hate
this one:

  http://groups.google.com/group/comp.lang.python/browse_frm/thread/e46de4596e93188b/


Raymond
@raymondh