## Wednesday, May 7, 2014

### DE Prof Master Post

To celebrate the end of the semester, allow me to present to you a master post of my differential equations professor's (usually unintentionally) humorous sayings:

v  It’s falling because that’s what things do.

v  A differential equation is something with a lot of x’s.

v  If that’s a sense allowed in the English language.

v  Stand back! I’m about to do some basic arithmetic!

v  I don’t have your tests graded yet. They take time and… - (student) Excuses. – Oh, so you want to me grade them like I do finite – just get drunk and start marking them all 0 or 50? – (student) No. We’re good. Take your time.

v  Say you have p sheep and some of the sheep kill each other. These are vicious sheep.

v  Partial fractions! We should be having traumatic memories of Cal 2 right now.

v  All models are bad, but some are useful.

v  This dry-erase marker is larger than an atom.

v  We can employ the method of… whatever to solve that.

v  There’s a quote… the shortest path between two truths passes through the complex plane.

v  You know, I don’t like Roman numerals. Roman numerals are stupid. *rubs it out and puts a 1 instead*

v  Let’s exponentiate this.

v  Any questions on how to find T? I hope we only have to find it for T, not coffee. *takes a sip*

v  I think f needs to be continuous for this theorem. Eh, I don’t care.

v  Uh-Oh. I’ve got c1and c2 switched in my notes. We’re in trouble.

v  I’m not an expert on differential equations. I’m just teaching this class because no one else wanted to.

v  Is everyone kind of okay with this?

v  Are you not entertained?

v  Okay, just pretend I’m allowed to multiply. Turns out I am. There’s probably a theorem somewhere to prove it.

v  We will solve this for the general solution, which is the answer of… whatever form for all questions like this.

v  (on SIR epidemic model) A recovered individual may or may not be dead. This model includes the dead people in the recovered. They are no longer infectious and are immune to further infection. I guess they’re not zombies, since they’re no longer infectious.

v  (on Laplace translation theorem) This theorem will not tell you how to calculate the Laplace transform in Spanish. De transformada de Laplace. No, we mean geometric translation.

v  This is an important theorem, which we won’t prove. Hooray.

v  It’s a fact from… somewhere… that an irreducible quadratic can be written as a sum of two square. You probably remember from algebra, how you could write it with arctan… Well, we’re doing something else now.

v  It will be the solution, the only solution, by some uniqueness theorem.

v  Okay, over here I have DE world, and over here I have Laplace world. This is the left side of the chart, and this is the right.

v  First I have to kill that 2 in front of x’.

v  This is one of our favorite methods from Cal 2. And how many times do we need to use it? Dos!

v  Is everyone okay with how we found x? The battle for x is over.

v  I think there is an arbitrary constant somewhere that I missed that’s important. Sorry, guys.

v  Why did we solve for F(x,y)? – (student) Because you told us to.

v  How about #4? Wait, I think we did #4 in class. How about #6? No, it looks like #4. Let’s do #8.

I think I'll actually miss this teacher...

In Pace Christi,

Elyse