The Unofficial
18.02/18.03
Quote Book

10–22

I could call that r, but I'm afraid to, so I won't.—APM

Let's imagine the circle instead of trying to draw it.—APM

The gradient...what? I just said the gradient!—APM

Proceed by the seat of your pants...or whatever you're wearing!—APM

10–26

In just shutting your eyes and following fundamental theorem of calculus, we are led into a grievous error.—APM

Write it in terms of differentials, so that chemists and other such people can understand you.—APM

The integral of wah blah wah wah blah...—APM

If it makes you more comfortable to write λ=t, y=1−t², well, get over it!—APM

So the answer—what?!—APM

I'll have enough time before −3 minutes at the end of the lecture.—APM

If I wish to be extremely pompous, and of course I do...—APM

Put this in your notes. I don't want to write it on the board—I got no room!—APM

Whoops! We have a collision of equations here!—APM

By the 18.02 chain rule, not by the piddley one you learned in 18.01.—APM

If you give it to a particular chemist, and by chemist I mean a particular branch of MIT, probably all of MIT except the math department, they'd say, "What? There's no proof there!"—APM

The process by which you got from here to here is highly shady.—APM

10–28

And the answer is...no...but for all intents and purposes, yes.—APM

And the answer is...it's already on the board.—APM

It's TRIVIAL.—APM

THIS is a formula.—APM

Given an infinity of paths to choose from...there's a tendency to sit down and despair: "Which path am I supposed to choose?!"—APM

Get over it now!—APM

Mathematicians have one, but it's of no use to the rest of the world.—APM

It's good enough for awhile, till it's not good enough anymore.—APM

I now know the magic value of a.—APM

10–29

While the ant is walking around I'm on the inside changing P and Q like mad...there I am changing P and Q, and the ant thinks nothing has happened.—APM

If you've got a hairy line integral around a simple curve, magic things happen.—APM

You know you know, but you're not gonna say because you're afraid the other guys are gonna get you after school...—APM

Of course you get the answer if you're lucky.—APM

I could have made it even hairier, but after a while I decided enough was enough.—APM

Ok...that's unfortunate...no! Because we have Green's theorem to save us!—APM

Put that down in your notes...I don't want to write it down.—APM

11–2

I'm in trouble, not deep trouble, just puzzled...which I just experienced.—APM

No one would believe it was true unless it was proved. Unless you accept authority, which you shouldn't.—APM

There's no way of learning that except by brute force.—APM

Of course I should try to confuse you just so you'll get unconfused. No, lets not do that.—APM

I'll do it rapidly and you'll be just as satisfied if not more satisfied.—APM

It's easy to say plus or minus.—APM

After a while it's not so tiny anymore and all bets are off.—APM

Nor has anyone ever proposed to me...—APM

Green's theorem—the one we know and love.—APM

It's an...it's an...it's an abstraction.—APM

Per per per per unit length per second.—APM

What goes in must come out, if the fluid's reasonable like H₂O.—APM

M had a name change—APM

Something unknown to all these little ants floating on their little boats is, it's raining.—APM

The RHS represents what God sees from above.—APM

11–4

Green's theorem is true. It's us that are false.—APM

Of course it does...erra erra.—APM

I can't position an any at the origin. That'd be the black hole, or the anti-black hole.—APM

In physics they can't calculate any line integrals and wouldn't know how even if they wanted to.—APM

It's exactly what gives the secret guy from above the ability to be pumping in (with a thin, hyperdermic needle).—APM

11–9

I don't think that's z=y. It is, because I declared it to be z=y!—APM

An equation like nothing I've ever seen before, but...courage!—APM

The evil song and dance of limits.—APM

11–12

That's not a bad integral. That's a good integral.—APM

Which piece of cantaloupe would you rather have? This one! Unless you don't like cantaloupe...—APM

I keep integrating until I get to this magic moment!—APM

Which θs do I want? Which ψs do I want?—APM

Life can only get better after this.—APM

11–18

All theorems have three names. A French name, a German name, and a Russian name—each nationality having claimed to discover it first. Once in a while there's an English name, too, but it's always Newton.—APM

If an any could visit every part and never find anything peculiar...—APM

None of these are any good. All of your suggestions are terrible.—APM

It's one, masquerading as δz/δz!—APM

If an ant would fall off, then it's not a closed surface.—APM

Someday you have to grow up and use the same variable for something, well...today is that day.—APM

You didn't tell me. That's your answer to me, not my answer.—APM

Nonetheless, it's useful despite being your favorite topic.—APM [Regarding the independent chain rule]

That long song and dance about Jacobians.—APM

It's better to keep it out and hope for good things.—APM

Half the time it must be pointing up, half the time it must be pointing down. Except when it's sideways.—APM

I know you would fall off a cube but the ant wouldn't fall off the cube and the question is whether the any would fall off the cube.—APM

N. N is an integer.—APM

11–19

I checked a few engineering books and they're full of it!—APM

What you can say is, I've done an experiment which disproves (the fact that heat flows from hot to cold). But everyone will think you're a crack pot.—APM

On the other hand, the more I say, the less you'll understand.—APM

If you're upset just pretend you're in some foreign country where they write zs as xs.—APM

Stuff is the same as thing.—APM

11–23

One only understands things the 2nd time around, which is why you have to keep taking mathematics, so you understand what you did before.—APM

So never stop taking mathematics.—APM

All I have to do is change the E to F which just involves erasing the bottom line.—APM

That's not right. Well, it is right except it isn't quite...—APM

Now we're up to today.—APM

11–30

Ugliness supersedes all rules of grammar.—APM

I stood on my head telling you to never substitute into that formula.—APM

If you want to be babyish you can put it in the notes but I'm not gonna write it and subject myself to shame.—APM

My apologies, so let me ruin your notes.—APM

I propose to do things entirely in your heads.—APM

-ix is a general suffix, as in suffix.—APM

Achoo!&mdashAudience member

Excuse me...uh, excuse you!—APM

Numerical calculations of an ODE was a job that took all summer.—APM

#1, #2, #3, #4, #5 in that order.—APM

2–14

You are under fake moral obligation to solve.—APM

We don't bother with details from everyday life in here.—APM

That is the one solution that separated the upward-going sheep from the downward-going goats.—APM

Mathematics is the art of accurate reasoning on inaccurately-drawn figures...let that be our motto.—APM

2–16

This is a box. They always call it a...you know, a box!—APM

A good spring—not the bad kind.—APM

You can solve pairs of simultaneous linear equations, except when you can't.—APM

2–18

Since you did me the honor of coming here after what I'm sure was a grueling 8.02 exam, let me return the favor.—APM

That's the way they look—start out bravely and then die away.—APM

I could gloss over this point but I wouldn't be able to sleep at night if I did.—APM

A little overkill doesn't hurt much.—APM

Now we have a genuine, good, bonafide equation.—APM

2–22

It's like one of those annoying crossword puzzles.—APM

Now where am I? Damn! I haven't made any progress!—APM

2–23

Who would have thought it? I did! I knew it all along! Ha!—APM

dx dx dx—APM

My galloping senility—APM

ii...it's the most perfectly imaginary number you can imagine.—APM

Put that in your notes! It's privileged information since you came to lecture.—APM

I'm wondering why I didn't ask you to do it for homework, but I'm getting soft.—APM

Solutions die as time goes on as opposed to living things which thrive and multiply and are fruitful and all that...—APM

On matlab, you'll believe it when you see it. Or no, you won't, but it's the best I can do.—APM

In the end, the dying exponential takes over and flops down listlessly to zero.—APM

Complete in 29 words or less, and send in with two box tops or a reasonable facsimile.—APM

Your exam will be reasonable, but I've said that before and turned out to be lying.—APM

2–28

[after reading Hale Bradt's 8.02 notes on the board from the previous lecture] Gotta stay one step ahead of you-know-who!—APM

This isn't gonna be a long song and dance...it's only gonna be about five minutes worth of song and dance, but I'm still gonna call it theory.—APM

They form a magic little charm circle that you can never get out of no matter how much you differentiate.—APM

Bad means not special.—APM

Some function of...er...daah!—APM

Again, the grammar defeats me entirely.—APM

You differentiate tan and get sin again, with a sign in front, or a funny little negative thing...—APM

It's important to learn to do calculations in a systematic way. I don't know. I can't finish the sentence!—APM

3–1

Armed with these two formulas you can do any problem!—APM

I now have to decomplexify...ugh! That's not a word...except within these hallowed walls!—APM

I'm doing it so that you'll learn them. So when you don't learn them at least you'll know that you're doing something wrong.—APM

That's gonna be a two cup of coffee problem.—APM

I'll complexify it this way...heh heh! And make it simpler.—APM

This is the second magic formula that will enable us to do anything.—APM

I have to prove it because nobody would believe a formula like that.—APM

Argh! This is absurd! Two mistakes in two inches!—APM

My mathematical conscience, since I've spent so much time writing pseudo-physics on the board, won't let me just write the formula.—APM

The Germans 100 years ago wrote the best text books...They were experts of pedagogy.—APM

I don't make a fetish of induction. I'm not knocking it.—APM

3–3

Motivation in the middle of the period!!—APM

You write in the word equation. I want to use as little chalk as possible.—APM

When I was a fraternity boy I had to memorize the Greek alphabet forwards and backwards. I reject that part of my existence.—APM

Of course, you have to apply the operator to both sides to preserve the peace and quiet.—APM

3–6

They're annihilated by the derivative operator!—APM

There is a theorem now which has to be invoked...I now invoke the theorem.—APM

Put this in your notes! And the second reason is...even if it weren't it would still be okay because...okay. There is no second reason.—APM

3–7

I'll be able to get it all in if I talk twice as fast as I am now.—APM

This is where the book and I part company.—APM

3–8

We're now going to calculate the 2nd log polynomial...grr! Remember, you saw it here first!—APM

To give the devil his due, he was a nice man, actually.—APM

There is no advantage, okay, stop me from saying this, but there is no advantage in copying, copying, copying.—APM

Times doddle-y. Or was that diddle-y?—APM

I'll let you out early...you know, as soon as you stop liking culture.—APM

3–10

This is my way, and it's going to be your way also.—APM

Why? Because if you don't, you'd better!—APM

Computers get the wrong answer, only people can get the right answer. That is why you are. Computers will always get the wrong answer to that.—APM

Zero is always less than one!—APM

If I just inspired two of you to learn it, that would be double the number that would normally know it.—APM

We've been away from differential equations too long. My God! Half an hour and I'm getting withdrawal symptoms!—APM

6/20? Crazy number!—APM

Fair answer, but the wrong one.—APM

In practice, there's no difficulty with that except sometimes when there is difficulty.—APM

The other terms are negligible compared to them, no matter how big they think they are!—APM

By abusive language, as the French say, infinity!—APM

You must always skip a step.—APM

I apologize for you that are theoreticians and know everything.—APM

If it converges when x=0, that is NOT considered exciting.—APM

3–13

Since I'm lecturing, I can get away with anything!—APM

You're at MIT...by definition, you can do that yourself.—APM

I can either be a good boy or a bad boy with this calculation.—APM

It's the variable lurking in the wings, waiting to come out and be the answer.—APM

Calculagate...calculate...—APM

Translation: blah blah blah blah limit limit blah blah blah blah.—APM

And n(n–1)...ha ha, stop! Aah!—APM

You put it all on one line at the cost of double the parentheses and triple the difficulty.—APM

Now, lets be a differential equations course.—APM

Watch this! It's real cute.—APM

Crazy, definite, improper...—APM

3–15

You agreed to let me be sloppy. Or I agreed that you would agree to let me be sloppy.—APM

Awww...sh...I don't want to baby you...even if you don't know what I'm doing, at least you'll feel like you're being treated like an adult.—APM

I'm pulling myself up by my own bootstraps. What are bootstraps anyhow? ...something you pull yourself up by...I don't know!—APM

We're on a desert island, we've got nothing to do. We wonder what the Laplace transform is. That ought to keep us occupied for 10 years at least!—APM

I can't explain why I'm doing what I'm doing, but it's really the thing to do!—APM

I'll write it down in little letters here that the back row won't be able to read, just to penalize them for sitting there.—APM

This is pattern recognition here...make your own pattern!—APM

Use any number. p you could use, if you were foolish!—APM

This guy doesn't go so fast that the other guy can't kill him in the race to infinity.—APM

(s²−1)y = s + 1/(s+1) = ...diddly stuff.—APM

3–17

Weird!—APM

Where shall I write? Where shall I write! Don't know!—APM

Goddamn! I keep writing t!—APM

We can't take a day off in 18.03. It's a really important subject, unlike others!—APM

This next line is the shakiest thing I will do all term.—APM

Gulp! There isn't going to be room!—APM

Since I forget it, when I do remember it I want to show everyone that I do!—APM

If you can see purple in the back row...if not, you shouldn't be sitting there.—APM

Use the desert island method! You have 20 years to figure out what this is so lets figure out what it is.—APM

Calculate it, all right? Lets do it! Grrrrr...—APM

Mentally psychological psychological mathematics.—APM

It looks horrible, but it's always darkest before the dawn...like any of you have seen dawns!—APM

3–27

Is the microphone on? No? Shit! ...I guess it must be on.—APM

If the EE department has another convention...bless them.—APM

It's not dramatic enough. Damn.—APM

Bah! I don't know what I'm doing!—APM

I was thinking of torturing you by calling it t. Well, lets call it t.—APM

3–29

How should you have thought of the Laplace Transform all by yourselves and covered yourselves in eternal glory?—APM

Ergonomically insufficient eraser!—APM

Almost all of the rest of the lecture has quotation marks around it meaning that it's not exactly mathematics and I'm not exactly responsible for it. I'm definitely not responsible for it. I'm definitely not responsible for it but you are.—APM

4–3

This is good enough to be in colored chalk!—APM

This is our system. Solve ME!—APM

It would be grossly, totally, absolutely wrong!—APM

Your book then goes on to explain how to do this with Laplace Transforms. Heh heh. I am very kind and we're skipping that, too.—APM

Nevermind what I did. Just write it down somehow.—APM

This must be in pink! Where's the pink? Or whatever the color is! It's called color-coding. The ideas in this course will be color-coded for the second half of the course. Since I have a brand-new box of chalk!—APM

It's one thing to watch a point moving. Grroowwerr!—APM

It has a bunch of vectors like this...aah! Stop me!—APM

I don't know if they're the most important. They're the only kind you can solve.—APM

This was the beginning of time. Namely, four weeks ago.—APM

4–5

The notes were written because I didn't think the book to be sufficiently intelligible.—APM

Start with this and by brute force follow it through with your nose.—APM

4–10

Fill in with curves near those, which are curvy.—APM

Now we're gonna pass the law of conservation of pink!—APM

The origin of which sits there forever, perfect, contemplating its navel.—APM

4–12

F = ma? It's always f = ma. No! ma = f! That's Newton's other law!—APM

Blah blah blah blah blah blah blah. Trust me!—APM

Some people need to hear my say it. Nobody likes to read. Even faculty won't read.—APM

Slowly—like moving through Jello.—APM

It's not fair that −2 should have a word but not +2.—APM

4–14

Computers have their own set of difficulties.—APM

So it remains, in splendid isolation!—APM

Mathematics is not a science.—APM

Unless you cheat, this is the region D. Ha ha.—APM

I'm just speaking common language, that's all.—APM

4–19

If I seem rather indecisive, it's because I am.—APM

You don't often see them. In fact, you do often see them, I've just been careful not to let you see them.—APM

Trust me...well, don't trust me! Do it! Look it up!—APM

I'm not exactly doing your homework for you...I'm just approximately doing your homework for you.—APM

4–21

The English is rather tortured, but you know what I mean...—APM

Not all theorems are green worthy! I have to be careful!—APM

Talk faster...no no, talk a lot faster! I can't be this slow, I mean, Hale Bradt would have finished the extended Ampere's law by now!—APM

4–24

The even series is the hyperbolic sinh, the odd series is the hyperbolic cosh...these crazy, drunk things!—APM

In a certain deep, but shallow sense...—APM

This is a danger curve! Be careful!—APM

Just relax and sit back and laugh!—APM

I can continue in this merry way...—APM

This'll be the only part of this lecture you'll understand.—APM

You'll understand in a second—not a second. Maybe five minutes.—APM

Now I'll have matrices and I'll lord it over my little sister.—APM

You get the picture, as they say!—APM

Now, all of what I've said is true, but it's misleading.—APM

[In a funny, low voice] As is well known by us in the field...that's to put you down so that you can't complain that you never learned it.—APM

Talking is of equal importance as computing, at least if you read books and papers and write them.—APM

4–26

Grahh! Grahh! Grahh! You're not supposed to erase, but once in a while, it's okay.—APM

The solution..."as is well known..." that's so you don't fight back!—APM

This cannot be a simplification. Of course it isn't. You don't have to do any less work...you have to do all the old work and a little bit of new work. It's just a change in language.—APM

5–1

Just to mutter for two minutes—oh, I can't mutter for too long...lets mutter at the end of the period, or else I'll mutter next time.—APM

[In singsong voice] You do hear...bah bah bah BUMM!!!—APM

I don't think you'll have any trouble following it, it'll just seem mysterious but that's fine. That's the way mathematics is.—APM

For the rest of this period, t and x are the same letter.—APM

5–3

"Ah ha!" he said in Latin! He covered himself in ego and glory.—APM

Here's my function. I'm gonna calculate the thing of...thing means Fourier series.—APM

5–8

I know in advance that I won't need it, so heh heh. [Writes "heh heh"]—APM

Oops...I called that A_n. It was supposed to be B_n...you're adaptable, right? I know you're not adaptable, but be adaptable.—APM

Your middle ear is a spiral filled with fluid. A sort of pink fluid.—APM

5–10

[Regarding the final exam] It won't be to pick your favorite differential equation and explain how it changed your life.—APM

Aah...sigh sigh sigh...—APM