ProgrammingMethodology-Lecture27.pdf

Programming Methodology-Lecture27

Instructor (Mehran Sahami): So welcome back. Wow. That’s a little loud. To our last

week of cs106a. Of course, it is another fun filled exciting day despite it being our last

week. We’re getting down to the end. We have class today, there’s class on Wednesday,

there’s no class on Friday. So next time will be our last day. But a few announcements.

There’s actually just a load of announcements because we’re so close to the end of the

quarter. First announcement, there’s one handout, which is your section handout for this

week. There are still sections this week, so despite the fact that we don’t have class on

Friday, still go to your sections this week.

There’s a couple problems on the section handout, as well as the sectional will just be a

general review for the final exam in case you have any questions. That’s a good place to

ask them. Also it would be a good place if you want to ask some questions say, about

[inaudible] for example, the last assignment. Just wondering, how many have started

assignment number seven? Wow, good to see. Anyone done with assignment number

seven? A couple of folks. That’s good to know. I might talk to you afterwards as to how

much time it actually took you, but hopefully, it wasn’t too painful. The graphics contest

was due last Friday. The winners will be announced in next class, so Ben and I actually

took a first pass already over all the contest entries. There was actually some very

impressive entries in the contest. Things you were just kind of jaw dropping, like, go and

show them to other faculty in the department because they’re just that cool. But this

afternoon we are having our staff meeting with all the section leaders and they will

actually be the ones voting and deciding on the winners in each category. So we’ll give

them the short list and they’ll make the final determination, and then on Wednesday, I’ll

announce it to and I’ll check with the winners of the contest to see if they’re okay

demo'ing it. But if they’re okay demo’ing it, then I’ll show you the winning contest

entries as well, plus on Wednesday we’ll have the random drawing to give away the last

sort of grand prize. But if you didn’t happen to win, just for entering you still get an entry

into the grand prize or you could just get a free 100 percent on any assignment in the

class including the final exam. So assignment number seven, we just talked a little bit

about. Since it’s due the last day of the quarter on Friday, but we don’t have class that

day, it’s just electronic submission. So if you’re wondering about what do I do with the

hard copy, you don’t need to do anything with the hard copy. We just need electronic

submissions.

For the other assignments in this class, we requested that you turn in a hard copy because

when you did interactive grading or if you’re a section leader to write comments on, we

actually had something that they could mark up. For assignment number seven, because

it’s due the last day of the quarter, there will be no interactive grading for the last

assignment so the down side is there’s no interactive grading for it, the plus side of that is

that you don’t need to turn in a hard copy because we can just take a look at your online

submission to figure out functionality and other kinds of things. And just as a reminder,

even though it wasn’t clear that was on the handout, like, right on the front the last couple

days, no late days on assignment number seven. Just in case you’re wondering. So final

exam, it’s time to start thinking about the final exam. Finals are next week. You probably

know that, but just in case you didn’t, the final exam is just like the mid-term. It’s open

book and open notes, so you can bring in your text book for the class. Feel free to bring

in all print outs of all your programs, all the notes you’ve taken in the class, all your

handouts. That stuffs all open, but just like the mid-term, it is a closed computer exam. So

if you have a laptop or a PDA or whatever, you can’t use that during the exam. Same

rules basically applies to the mid-term. And we’ll talk a little bit more about the final

when we actually do review for it next class.

The regular final is scheduled for Thursday of finals week. That’s December 13th, 12:15

to 3:15 P.M. in Kresge Auditorium, which is the same place we had the mid-term. One of

the only rooms large enough to actually accommodate us, and the alternate has been

scheduled. So alternate final is December 12th, that’s Wednesday of finals week, 3:30 -

6:30 in the afternoon, also in Kresge Aud. So this time seemed like a relatively unpopular

time for other final exams. And you’re free to take either one. So you don’t need to send

me an email saying you have a conflict with the regular exam or whatever. If you just

want to get done with your finals earlier and you want to take the alternate exam, you’re

just welcome to take the alternate exam. But only take one exam. So you can pick one,

and just one. That’s just life in the city. Okay. And if you’re an SEPD student, I

announced this last time, but I’ll announce it again. I’ve already gotten email from one of

you, which is a good thing. To email me by 5:00 P.M. December 5th, that’s Wednesday

if you’re planning on taking the exam at your site. If you’re gonna come in for the exam,

you don’t need to email me. You can, feel free to email and say, “Hey, man, I’m gonna

come into campus and take the exam.” And you’re welcome to take it at either one of

these times as well as if you’re out in SITN. But if you plan on taking it at your site, send

me an email. Also, let me know the name and email address of your site administrator so

I can send the site administrator your exam to administer to you. So that was just a load

of announcements.

Any questions about anything before we delve into our next great topic? All right. You’re

feeling okay. Good. So a lot of today’s class is actually about life after this class because

we’re getting pretty close to the end of this class. So one of the things I want you to just

kind of know about and so you can think about it, are what are some of the options that

are available to you afterwards. Whether or not you’re just thinking about declaring a

major or if you’ve already declared a major or you just want to get sort of a lay of the

land of what’s this whole computer science thing all about. Because probably the biggest

thing I would stress, despite the fact that you just spent the last nine weeks programming,

is computer science is not computer programming. Okay? A lot of time the two get

equated, but if it was called computer programming, this class wouldn’t be called

programming methodology, we’d just call it something like programs that work, right,

and we wouldn’t worry about style and all this other stuff, and good software engineering

principles, and at the same time, computer science wouldn’t be called computer science,

it would called something like programming. Right? And it’s, like, “Oh, what did you

major in?” “Oh, I majored in programming,” and that’s like, when you say, “Oh, I’m

sorry. I think you can get shots for that kind of thing now.” Because it’s not just about

programming. There is programming in computer science, but there’s actually a science

to the field and there’s a lot of things that go on outside of programming and that’s what

it’s important to, in some sense, appreciate. So if we think about life after this class, let’s

first kind of deal with some of the short-term logistical kinds of things. Like, you just

took this class; you might think, well, there’s probably a couple things you think. You

think, “Hey, Miron, that was kind of interesting, I might consider taking 106b.” You

might consider, “Hey, Miron, that was interesting, I might actually considering minoring

or majoring in computer science.” And you might say, “Hey, Miron, that was interesting,

in the same way, for example, that dropping a brick on my head is interesting, and I’m

gonna run screaming.”

And if you’re thinking the third option, I apologize, because that was not the point of this

class, but here’s a few things that you can potentially think about, even if you’re in the

third option and definitely some things to think about for the first two options. And I

guess there was also that option of the, “Oh, I got the general education requirements out

of the way and now I will go on figuring out what to do with the rest of my life,” and if

that’s the case, you should pay attention as well. So what happens after 106a? So here’s

cs106a, this is where we’re all sort of happy, and we’re scrappy and we’re making social

networks, and life after this kind of, you know, your next immediate step is actually

pretty clear. There’s a class cs106b, that’s called Programming Abstractions, which is the

next class to take. And that class is on a language called C++, so you’ll learn a whole

new language, although, you’ll realize when you actually CC++, that a whole bunch of

things in it are just the same as Java. Whole notions of parameter passing and methods,

and decomposition and objects, all those same things exist in here. Okay. But you also

will get with this class called Programming Abstractions because, so far, what we’ve

done is used a lot of extractions. There you get into a whole bunch of tradeoffs with how

you can make things run more quickly versus perhaps using more memory versus

different kinds of programming techniques that actually come up. There’s also some

really cool ideas that come up in here, which are just sort of mind blowing ideas, which is

the notion – for example, one of them is called recursion, which is so far we have

methods and methods call other methods and they call other methods. What if a method

called itself? That’s kind of weird, Miron. Why would a method call itself? Because some

functions are defined in terms of themselves. Right?

If you kind of think about the factorial function – anyone remember this function? The

“N” function. Right? This is N factorial. And all this really is – sorry if I just shattered

your ear drums, is N times N minus 1 times N minus 2 times….times 1. You just multiply

everything together. That’s where [inaudible] all about. You can define a function in

terms of itself. And it turns out, yeah, a factorial, that’s kind of a simple way to

understand it. It turns out that this is a hugely powerful concept that allows you to do all

kinds of things, and this is kind of another cool thing you get in cs106b. Okay. Now, you

might say, “Okay, Miron, that’s still sounding like programming to me, even though I’m

learning these cool concepts, isn’t that just a programming class,” and in some sense,

yeah, this is a programming class. There’s other options that are also available to you

now that kind of fall into the category of being part of the CS major or the CS minor. A

set of classes called cs103. And cs103 come in a different couple different flavors, like,

vanilla, grape and pork – no, they come in those in a, b sequence and there’s [inaudible] –

I can’t think of anything in the world that would come in those three flavors.

And this is really a class that in some sense is about discrete math. And you might say,

“Oh, gee, Miron, besides your class, I’m taking calculus and that’s about as much fun as

sliding down a 50 foot razor blade. Why would I want to do that again? Not on the sharp

side, right, just imagine the other side, like, the flat side of the razor blade and it’s been

made slick and it’s like a big slide. It’s fun. Wait until all my friends in the math

department see that. Anyway, why would I care about this discrete math thing? Well, first

of all, this is an operative word here, which means this little symbol that you have grown

to know and love, our friend the integral, just nod around, right, this is all discrete, this is,

like, “Hey, you know what, what we want to think about our some things that are useful

to us in a computer science context,” and computers at the end of day are digital objects.

Right. They have ones and zeros, which means there’s a whole bunch of things, like, sets

for example and logic that come up in these things. But there’s also interesting ideas that

come up in here, like, computability. In these classes, you get exposed to some things like

some of the biggest open problems in computer science.

Now, there isn’t time to go into what some of the biggest open problems in computer

science are, but there’s a problem called the P = NP problem. Right. And this is a big

question mark. Basically, we just don’t know if these two things, one of them named P

and the other one named NP are equal to each other or not. And you’ll find out what

those are in the class and you might say, “Okay, Miron, why do I care about that?”

Because it turns out this little problem here, has a $1 million prize associated with it. And

it’s simple enough to explain that after having had 106a when you take these next two

classes you’ll actually get exposed to this problem It’s one of things that’s, like, a minute

to understand, a lifetime to master. And no one’s mastered it yet. But in some sense, this

is also a problem that’s only about 35 years old. Maybe just slightly older than 35 years

old. So it’s not like this problem that’s existed for, like, hundreds of thousands of years

and, you know, cave people were writing does P = NP on stone tablets. This problem

actually came to the floor and people realized it was an important problem in the 70s,

which means it’s possible that it’ll be solved in your lifetime, and it’s possible that you

may be the one, presumably, solving it in your lifetime because it would be difficult to

solve it if it wasn’t in your lifetime.

So even if programming, by itself, doesn’t necessarily turn you on, but you think, you

know, programming is interesting, is there also some deeper science or some

mathematics because for a lot of people, they didn’t necessarily get exposed to computer

science earlier on, but they did get exposed to mathematics, this might be the kind of

thing that really turns you on. Now, you might say, “Okay, Miron, math doesn’t

necessarily turn me on, programming turns me on.” Besides that 106 class, what other

options are there? There’s two other classes, cs107 and 108. And these classes, basically,

look at building, in some sense, larger scale systems, so this involves object oriented

systems and in some sense, building larger applications. So you build some things here

which are outside the scope of a one or two-week project, like, you might spend four

weeks on a large project in this class by the end and actually build a fairly substantial

application, and 107 looks at a whole bunch of issues, that in some sense, we like to think

of as lower level kinds of issues, but it involves a lot of programming and it gets into the

nuts and bolts as to how does the software sit on top of the hardware of your machine and

how do these things interact and getting into understanding memory better and whole

bunch of other things.

And if you think about this set of class, like 106a, b, 103a, b and 107, 108, if you were to

take that set of classes and add to it 2cs electives, that’s the minor. Okay. So the minor is

basically these six core classes. You need to take math up to math51 I should say as a

little side note. Just in case you’re wondering. That’s just something, that, you know,

we’re not responsible for that, it’s just kind of required. And then two cs electives beyond

this kind of stuff and then you’re getting a minor. Okay. So if you want to kick it up a

notch beyond a minor and think about the major – actually, I’ll just leave this up. Two cs

electives, you sort of add that all together and it equals the cs minor, which is kind of fun.

Okay. Now, if you want to think about besides just a cs minor, potentially, actually

majoring in cs, you might want to think about, “Okay, first of all, what are some other

things that I can do in computer science beyond the introductory classes,” and there’s a

whole bunch of things. There’s something that we call artificial intelligence, or just AI,

for short. And there’s a whole bunch of aspects of artificial intelligence. That’s sort of the

highest level.

It’s the notion of trying to make your computer work more intelligently, and in some

sense, appear to be more intelligent, sort of on the order of the intelligence of a person.

But really this has a whole bunch of sub fields to it, for example, robotics and various

other things such as computational biology, there’s a lot of computational biology that’s

ground in artificial intelligence. Data analysis and I’ll show you some examples of these

as we go along. And this is today, and there’s a whole bunch of people in the world who

are wondering what happens tomorrow. And if you can do slightly better than 50 percent

predicting what happens tomorrow based on analyzing all the data from today and before,

you make tons of money. Okay. And if you wondered is this really the case? Yeah, in

fact, anyone heard of a company called D.E. Shaw? Yeah. Anyone. A few folks. Yeah.

It’s David Shaw. He was actually a grad student at Stanford in computer science. And

this whole – I wouldn’t say he started this whole thing, this actually existed long before

that, but there’s whole companies whose entire business is based on the notation of

quantitative analysis and guess who are a bunch of people that they employ? Computer

scientists who go and do the data analysis and actually figure this out. Okay.

So the application and understanding what are all the variables that you care about and

the information that exists in the stock market that you can extract and model with

different kinds of algorithms to make your prediction, is all part of what computer

science is all about. Besides, AI, there’s various other kinds of little areas. I’ll show you

some more pictures, like, robotics. Anyone heard of Darpa Grand Challenge or a little

robot called Junior or Stanley? Yeah. Oh, Junior, he’s so cute. Because it’s a robot, that

in some sense, is a car. Right. And there’s no reason why a car can’t be a robot. Just think

if Carol had wheels on it, and instead of move…you had move at 60 miles an hour, you’d

be doing the same thing, except you’d be doing it in a simulation. This is Stanford’s car,

Junior, and this is a car that’s basically a robot. It doesn’t have a human driver, at least

most of the time. Right? It has things like various kinds of sensors on it, various sorts of

radar and other kinds of laser range finding that sense what’s going on in the world and

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