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Re: ROCKET ERROR



At 11:39 12/29/99 -0500, David Bowman wrote:

Regarding Ludwik's recently reported results for a rocket problem:
...

[Ludwik]
I did this and the new results are in very
good agreement with the theory...

[David]
I'm sorry to be so pedantic here, but your results *are* the theory
...
Numerical simulations are not compared to theories in the sense that
experimental results are compared to theories (i.e. as tests of the
theories, the experimental results, or some combination of both).
Rather, they are (to the extent the numerical techniques and algorithms
are reliable solution techniques) predictions *of* those theories....

David Bowman

That's what I like best about Ludwik.
He may take a lickin' but he keeps on tickin' :-)
(to coin a Timex tag).

Persisting through critiques is a quality I associate with
some of the greatest investigators.

On the question of numerical simulations, I admit to hungering for
the time delta as the iterated quantum rather than efflux mass in
Ludwik's model.
The assumption was a constant mass flow rate so this was I suppose
an implicit simulation in time.

On the question of simulations - can they ever said to be in
agreement with theory? - I recall in bulletin board days a person
would sometimes post puzzles of conditional probability.

Here's one in the general format.
"I add 6 blue marbles to a barrel containing 200 red marbles and 15
yellow ones. What are my chances of pulling at least one yellow marble
and no blue ones in three tries, selecting three at a time, and
throwing them back?

There was of course a formal approach. But I persisted in running
Monte Carlo trials to obtain an answer to the nearest tenth percent.
I suspect that here I was not mechanising any theory of conditional
probability - I was running an actual experiment.




brian whatcott <inet@intellisys.net>
Altus OK