# Exam III tomorrow

Hi everyone, just wanted to holler and give you the rundown on tomorrow’s exam. It’ll cover all the material we’ve done since Exam II, which is the stuff from the lecture notes posted in the Documents tab, plus sections 4.2 and 5.3 from the textbook (mostly 5.3 pseudoinverse stuff). If you want to do well, you should know how to do all the problems from the homeworks and the practice problems, including:

– Proving that a vector x is or is not in the span of a set of vectors

– Definition of basis, linear dependence, span

– Finding the solution set of an underdetermined, consistent system

– Finding bases for row(A), col(A), null(A)
– Knowing rank(A), nullity(A)

– Proving a set S is a subspace (use the theorem by showing that S is the span of a set of vectors)
– Proving a set S is not a subspace (use a counterexample (with numbers) to show that S violates one of the requirements for being a subspace)

– Proving that T is a linear transformation (use the theorem by showing T is a matrix transformation)
– Proving that T is not a linear transformation (use a counterexample (with numbers) to show T violates one of the requirements for being linear)
– Knowing the domain, codomain, range of T

– Calculating best approximate solution of an overdetermined system by using the pseudoinverse

For the proofs and other analytical parts of the test, the most important things to understand are the rank theorem, the fundamental theorem of invertible matrices, and the fact that the matrix-vector equation Ax = b means that b is a linear combination of the columns of A, where the coefficients are the components of x

I think about truffle cheese a lot more than is probably normal. Now, you know I am a bit of a cheese nut so this probably comes as no great shock. (Side note: “cheese nuts”would be a great snack, right? Wait, would they? Would they just be gross? I guess I’d probably have to figure out what they are first. Maybe a nut that is embedded in some cheese. Probably not that great. Wait maybe then you fry it? Better, definitely. But good? I’m not sure. I feel like cheese and nuts, while each excellent on its own, ought not be mixed, kind of like Chinese food and cheese. I’ll have to spend some time in the lab and get back to you on this.) However, I believe that (abnormally large volume of cheese thoughts aside) my ratio of truffle cheese-related thoughts to non-truffle cheese-related thoughts is higher than the national average by statistically significant margin.

I think about a cheese called Truffle Tremor, which is made by Cypress Grove, of Midnight Moon and Humboldt Fog fame:

Midnight Moon is the goat gouda that you might recognize from a little store called Every Bodega In Williamsburg; Humboldt Fog is your momma’s favorite fancy cheese. They’re both actually pretty good, but snobs like me enjoy taking the piss out of people for enjoying them, then retreating to our dens of sadness to eat monk-crafted, limited-release, beer-washed smelly cheese while listening to our #veryrare vinyl of the Monkees’ Davy Jones strangling bats in a Lebanese cave.

Anyway, Truffle Tremor is basically Humboldt Fog minus the center ash line plus black truffles. It’s good because it tastes like cheese but it also tastes like truffles. Sounds simple enough. The problems arise in a truffle cheese when it overreaches. I bought a cheese at Trader Joe’s once that purported to be a truffle cheddar. The price was just \$6/lb, which should have given me pause (Truffle Tremor is \$35/lb at Murray’s, though I think only \$24 or so per lb (precut, though) at Union Market). What sort of truffles could they be using to keep the price point that low? As it turned out, there weren’t many truffles involved at all. There was truffle oil and truffle paste, but I felt them merely as truffle remnants, truffle shadows. Truffle memorie that linger only in imagined senses. In trying to be all things for all people — the common man’s reclamation of the princely food — this cheese betrayed itself. We all can learn a lesson from its failure — as Polonius advises, this above all else: to thine own self be true. If you are a \$6/lb cheese, be at peace with your nature. Do not cloak yourself in the vestments of a finer curd, but rather accept your limitations, and own them.

If you memorize the Norton Anthology of Poetry and a map of Africa, that’ll help with the extra credit on tomorrow’s exam.

If you memorize “You’ll Never Walk Alone” that’ll help win over the next Liverpool fan you meet.

# HW 10 / Snidely Whiplash

Lot on the docket for this email. First of all, the exam ii stats are thus:
75th percentile: 88
median: 79
25th percentile: 68
mean: 73.4

Also, I posted HW 10 yesterday morning, so get started on that immediately if you’ve not already done so. It’s really important. Essential.

There are some solutions up in the Assignments tab — to homeworks, exams, The Great Questions of Human Existence, etc.

Your third in-class exam will be on the last day of class — Wednesday, 3 December 2014.

The final exam is scheduled for Tuesday, 16 December 2014, from 8:00 a.m. to 10:45 a.m., in the usual classroom. It’s optional — if you don’t take it your grade breakdown will be

Exam I: 24%
Exam II: 28%
Exam III: 28%
Homework: 20%

If you do take it, the breakdown will be:

Exam I: 11%
Exam II: 16%
Exam III: 16%
Final Exam: 37%
Homework: 20%

I will drop the lowest homework grade when calculating your average, because I’m a sport and it’s The Right Thing To Do.

Look, I know I’ve been derelict in my duties. You’ve bided your time, patiently awaiting a long-expected bonus fun time email to go with the weekly joy of a homework assignment. (Incidentally, “Long-Expected Bonus Fun Time Email” is the name of a Japanese game show, an American version of which Jakob Dylan is producing for Spike TV this winter.) And I’ve failed to deliver — for almost two months! I could sit around and make excuses — how I’ve been really busy, and I’ve gotten into Guiding Light lately which takes up A LOT of time, plus my neck’s been doing this weird cracky thing lately. Not to mention the beauty of the orange fall foliage has been really getting me down because it reminds me of how the best years of Jersey Shore are far behind us now. (My phone just autocorrected Orange for orange. Not sure if it’s suggesting that based on its presumption of my love for Syracuse athletics or famous Dutch royals. I’d ask Siri but she and I aren’t speaking since she questioned why I kept asking her to find those Kim Kardashian Paper Mag pics. “Why don’t you just save one and make it your background” she says. Because I don’t goddamn want to is why, Siri! What if my 8-year-old cousin Cordelia wants to use my phone? How do I explain that gigantic butt to her? That’s not something the prepubescent mind is equipped to process! Now do my bidding like a proper little servant program.) — but the truth is, saying “I didn’t have time” really means “I didn’t make time”. If you really want to do something, you find the time to do it.

I’ve had to do some intensive reflection these past weeks to get to the root of why I’d eased off the gas pedal of my prattling emails, allowing the city bus of our class’s amusement to take an unscheduled holiday in the Florida of, uh, only occurring occasionally in class when I tell the rare joke or story that happens to land. (That comically overwrought and only tangentially sensical metaphor brought to you by the podcasts I listened to this week — This American Life (which talked about a 1950s NYC bus driver who decided one day to bounce (with his bus) and take a quick jaunt to The Land of Nod aka Bosh’s Paradise aka your favorite state’s favorite state aka Florida), and The Bugle, which is a satirical podcast that loves employing metaphor in this way (though generally much more skillfully. Maybe I’ll try my hand again later this email. Since I have absolutely no idea where I’m going with this email, I’m not going to make any promises.). (Yes, I made that Land of Nod reference solely for the purpose of linking to Singapore by Tom Waits, the opening track to one of the best albums of the 80s, Rain Dogs. (Though saying a record is “one of the best albums of the 80s” is like saying one of your British friends is “one of the chillest members of the UK Independence Party”. (I’m just kidding, of course; there were plenty of artists putting out great music in the 80s — Joy Division, Talking Heads, The Smiths, Kate Bush. It’s just that they’ve become so synonymous with entitled Gen X pomposity and pretension that it’s tough to think of them without wanting to find the nearest copy of Less Than Zero and rip it up with my bare hands. Plus I wanted to make a UKIP reference — The Bugle is British political satire and like I said, I’ve been catching up this week)))

The truth, I’ve realized, is that I’d gotten afraid. Afraid that I’d never again realize the greatness (by which I mean “length”) of the legendary (i.e. “very long”) Ugolino email, or the nearly as astounding virtuosity (I am also using this word to mean “length”) of the captivating (i.e. “almost, but not quite, as long”) Louis Vauxcelles email. Then I said to myself
“HEY! GET IT TOGETHER, LETTERII! THESE HOMIES DESERVE THEIR FREAKIN’ EMAILS!” and I replied to myself
“You know what, you’re right. And I appreciate your not swearing around Cordelia. It’s bad enough she saw those Kim Kardashian butt pics open in my Chrome browser when I leant her my phone to look up the word ‘obstreperous’. Let’s let her preserve the innocence of youth for a while, in the face of the go-go-go media Twittersphere and the ever-tightening grip of Snapchat and Yik Yak and Whisper and GreenDart and Whipple,” and then I replied back, a little confused,
“Wait, those last two aren’t apps,” to which I responded ominously:
“Not yet.”

Look, those previous emails took me about 10-20 hours to write, which is not time I have these days. What I mean is, lower your expectations. Just look at this email — completely self-absorbed and self-indulgent, not informative about anything culturally or culinarily interesting, and, worst of all, totally bereft of trippy visuals. In other words, I’m not saying these new emails are going to be any good. All I’m saying is that they will exist.

By the way, I just looked up GreenDart and Whipple, and they are both real things, though not apps.

# Exam 1 / office hours / platypus

So your exam is this coming Wednesday, 24 September 2014. It’s in the regular classroom at the regular classtime, and you’ll be with all the regular classfolks. I’m pretty excited about it. You should be, too!

I’ve posted a practice exam in the Documents tab. Go over and take a looksee. The solutions are there, too, but don’t look at those until you’ve done the exam, obviously. If you do, I’ll be really steamed, and you don’t want to push me because I’m close to the edge. I’m trying not to lose my head.

Check the syllabus for all the regularly scheduled office hours next week; I’ll also be available for help right after class on Monday. I think I’m going to see if one of the classrooms on the 4th floor of the library (e.g. W4550, or one of the others in that hallway) is empty so we can use it; otherwise it’ll be an al fresco session, because I love nature and the cool air of a new autumn.

I know what you’re thinking: “Yo teach, André Derain was the co-founder of Fauvism, where was the love for him in that last email?” Listen, Derain’s Fauvist work was dope, there’s no denying. Check that London groove

Charing Cross Bridge, London, 1906

Makin’ it real funky. But then after a few years he shut down the Fauve factory and started getting all into the Old Masters and making regular-looking paintings with like Browns and Greys

Window on the Park, 1912

and I’m just like ugh dude what happened, you used to be so chill, we used to get baked and listen to Oneohtrix Point Never together and now you just want to talk about ballet and drink cognac. And you know, I guess that’s cool and I ain’t mad atcha and now that I think about it some of these new joints are actually pretty fresh

Still Life, 1914

but then hold up what happens next? You go off to Nazi Germany and tour around like everything is normal there, like they’re just a regular old country not one trying its hand at world domination and also committing some of the worst atrocities ever conceived. That’s wack of you, André. Maximal prop deduction.

# HW 4 / Grover

Your next assignment is now posted in the usual place. It’s due a week from today (i.e., 24 September 2014) at the beginning of class. Don’t forget you have an exam that day, too. Also don’t forget that it’s Scott Fitzgerald’s birthday. Go read Babylon Revisited, or at least drink some gin.

Probably wouldn’t hurt you to eat some Selles-sur-Cher, too.

Unless you’re lactose intolerant, I guess.

University is important, but for some people a nontraditional learning experience is preferable:

“If they ever come up with a swashbuckling school, I think one of the courses should be Laughing, Then Jumping Off Something.

# Lost netbook / fundamental theorem / homework / exams / rutabaga?

Hi everyone,

Someone left a netbook and a pencil case behind in class yesterday and a student from the class that meets at 5:30 in our room gave it to me, so I have it with me in my office. If it’s yours come by my office to get it. I’ll ask you what brand it is and any distinguishing characteristics of it to validate your ownership of it. If you can’t make it today, send me an email. I’ll bring it to class tomorrow if necessary but I’d rather not because I am physically weak and carrying even a small computing device is very taxing on my underdeveloped body.

I’ve posted the Fundamental Theorem of Invertible Matrices in the Documents tab, so go on over there at your leisure and take a gander.

For problem 2 of Homework 10, you don’t have to do a proof by contradiction. In fact, there is a fairly simple direct proof.

I will post an assignment tomorrow, but it won’t be collected, so it’s not really a homework. More like a review sheet for your upcoming exam 3.

Exam 3 (which is Thursday May 8th) is mandatory. The final exam (that is, the exam on May 19th) will be optional. If you choose not to take it, your grade distribution will be the following: Exam 1: 24% / Exam 2: 28% / Exam 3: 28% / Best 9 homework grades: 20%

If a kid asks where rain comes from, I think a cute thing to tell him is ‘God is crying.’ And if he asks why God is crying, another cute thing to tell him is ‘Probably because of something you did.'”

# Homework 2 – further clarification

For problem 3 in section 2.2, you can decide whether a, b and c are row vectors or column vectors. Just be sure to be clear about what they are in each part.

For example, if in (b) you say bB is well defined and in (e) you say Bb is defined, then make sure to explain the dimension of b in each case.

Alternatively, you may give the dimensions of a, b, and c in the beginning of the problem and then keep them consistent in all parts.

“My friend asked me if I wanted a frozen banana. I said ‘No, but I want a regular banana later, so … yeah’.”