Re: puzzle



Christopher Barber wrote:
> spinoza1111@xxxxxxxxx wrote:
> >
> > pete wrote:
> >
> >>spinoza1111@xxxxxxxxx wrote:
> >>
> >>
> >>>You're doing O(n) searches, times a linearly shrinking array, only in
> >>>the worst case. N/2 the time on average it finds U. This doesn't
> >>>transform order n^2 because it divides by a constant and not N but it
> >>>is none the less a significant reduction.
> >>
> >>Whatever O(n * n / 2) could possibley mean
> >>is what O(n * n) actually means.
> >>Constant factors aren't part of big O notation.
> >
> >
> > Of course not. But, n*n/2 != n*n for positive n: n*n/2 < n*2 for n>0.
> >
> It is not clear to me that you understand. O(n*n) == O(n*n/2)!

D'oh. As my kids would say.

I am very disturbed by your failure to read the post properly, and this
kneejerk reduction of discussion to the biographical issue of who
understands what, which, as I have said, makes this ng useless for
either discussion of technical issues or the generation of solidarity
or understanding among programming professionals.

For, I used the phrase "close to" as regards O(n).

O(n*n) == O(n*n/2), of course. But it's also the case for practical
applications that n*n/2 < n*n.


>
> The important point is that as the size of the data set doubles, the cost of
> the algorithm quadruples. Dividing by two doesn't change this.
>
> > The resentment here is of ability to explain, complementary to the
> > inability to read shown by O'Dwyer who read a claim for O(n) when I
> > said "close to".
>
> When you are taking about the O() notation, there is no such thing as "close
> to". Something is either O(n) or it is not. O'Dwyer probably assumed that
> you knew that.

It's obvious from the original post that I understand, and again, this
transformation of discussion into a childish attempt to score
biographical points is bull***. As are lectures on the "real world"
via email, for it is precisely in the real world that one discovers for
any number of reasons that one can't sort pragmatically but one can
delete, or vice versa, and in the real world you have to be able to
analyze, and discuss, algorithms without succumbing in the individual
case to crippling math anxiety or in the group case to childish attacks
of the form "you don't understand".

As in the case of Adorno's study of astrology readers "The Stars Down
To Earth", you come here and because of corporate surveillance, you
adopt Adorno's astrology reader's false consciousness: that of the
corporate manager to whom you doubtless report, who is forever making
judgements and takes no pleasure in his job.





>
> - Christopher

.