WordSteps
Есть вопросы?
закрыть

第20讲 | 麻省理工6.00 计算机科学与编程导论 2008年秋

00:00:00
OPERATOR: The following content is provided under a
00:00:02
Creative Commons license.
00:00:03
Your support will help MIT OpenCourseWare continue to
00:00:06
offer high quality educational resources for free.
00:00:10
To make a donation, or view additional material from
00:00:13
hundreds of MIT courses, visit MIT OpenCourseWare
00:00:17
at ocw.mit.edu.
00:00:19
PROFESSOR: All right, so today we're returning to simulations.
00:00:25
And I'm going to do at first, a little bit more abstractly, and
00:00:30
then come back to some details.
00:00:32
So they're different ways to classify simulation models.
00:00:38
The first is whether it's stochastic or deterministic.
00:00:53
And the difference here is in a deterministic simulation, you
00:00:57
should get the same result every time you run it.
00:01:04
And there's a lot of uses we'll see for
00:01:06
deterministic simulations.
00:01:08
And then there's stochastic simulations, where the answer
00:01:14
will differ from run to run because there's an element
00:01:17
of randomness in it.
00:01:20
So here if you run it again and again you get the same outcome
00:01:23
every time, here you may not.
00:01:29
So, for example, the problem set that's due today --
00:01:35
is that a stochastic or deterministic simulation?
00:01:40
Somebody?
00:01:42
Stochastic, exactly.
00:01:45
And that's what we're going to focus on in this class, because
00:01:49
one of the interesting questions we'll see about
00:01:51
stochastic simulations is, how often do have to run them
00:01:58
before you believe the answer?
00:02:00
And that turns out to be a very important issue.
00:02:03
You run it once, you get an answer, you can't
00:02:05
take it to the bank.
00:02:07
Because the next time you run it, you may get a completely
00:02:09
different answer.
00:02:11
So that will get us a little bit into the whole issue
00:02:14
of statistical analysis.
00:02:19
Another interesting dichotomy is static vs dynamic.
00:02:31
We'll look at both, but will spend more time
00:02:35
on dynamic models.
00:02:37
So the issue -- it's not my phone.
00:02:43
If it's your mother, you could feel free to take it,
00:02:45
otherwise -- OK, no problem.
00:02:50
Inevitable.
00:02:54
In a dynamic situation, time plays a role.
00:02:57
And you look at how things evolve over time.
00:03:00
In a static simulation, there is no issue with time.
00:03:07
We'll be looking at both, but most of the time we'll be
00:03:11
focusing on dynamic ones.
00:03:15
So an example of this kind of thing would be a
00:03:19
queuing network model.
показать еще
свой перевод
Работаем...
нет перевода