Math 307A   •   Spring Quarter 2013

May 31

Quiz 8 is up on the calendar; it is the final quiz of the quarter. It's just five questions about a function that is defined in terms of the step functions from Wednesday's class. You have until Tuesday at 11PM to fill it out, because I didn't give you much notice, but you should just go do it ASAP so you don't forget. As for the homework, by now you can do all of the questions from 6.3. Next week we'll do 6.4 and final review!

May 29

I just posted your seventh and final homework assignment for the quarter. I would highly recommend getting started on the first few problems from 6.3 (certainly the first four problems, possibly even the fifth and sixth using the formula from the end of class today). We'll practice these more in class on Friday, but the more you do ahead of time the more it will make sense in lecture. There will be one more quiz over the weekend, about the step functions u_c(t) that I defined today.

May 27

I mentioned this in class a few times last week, but just to announce it here too: there is a quiz currently up that is due tomorrow (Tuesday) night. It is on determining the right form of a function in order to take the inverse Laplace transform of it. There will be one more quiz this quarter, which I'll announce soon.

May 20

HW 6 is up, and it is due a week from Wednesday. Today's class has already equipped you to do the problems from 6.1. I'll return the midterm exams on Wednesday, and there will be a quiz on 6.2 over the weekend (see the calendar). Also, my office hours tomorrow will be from 3-5 in my office, ART 336, not the MSC. Finally, I posted the midterm solutions on the materials page.

May 13

I posted a handout containing some good data about resonance on the materials page. Please read it carefully before Wednesday, so you can ask me questions about it if anything is confusing before the midterm. Also, I posted a link to some great 307 videos (also on the materials page), and those might help you study. On Wednesday I'll summarize the highlights of each section, and then give you some problems to work on for the rest of class.

May 10

Quiz 6 is open; it is due on Monday at 9AM. It asks you to find the right form for Y(t), in several different situations. On Monday I'm bringing in a physics spring/mass demonstration to show you what happens when there is a periodic external applied force. Have a great weekend!

May 7

Quiz 6 will be over this coming weekend. It will be on the material from 3.5. Specifically, you'll have to determine the form that a particular solution to a nonhomogeneous differential equation will take (note: this will make more sense after the next two classes). This will be the last quiz before the second midterm. At this point I'm planning for two more quizzes after midterm 2, for eight total.

May 3

Quiz 5 is open over the weekend; be sure to take it before Monday at 9AM. After today's class you should be able to get started on most of the 3.7 problems. We haven't talked about amplitude, frequency, overdamping, or critical damping yet, but we will on Monday (or you can look in the book for a preview).

April 30

Quiz 4 is open; a link is on the calendar page. It closes tomorrow evening, 11PM. Quiz 5 will happen over the weekend. Also remember that HW 3 is due on Wednesday.

April 24

Solutions to the midterm exam are up on the materials page. I'll return your tests on Friday. Homework 3 is up, and covers the material from today and Friday and part of Monday. Also, I put up some useful information about computing your HW and quiz grades from your scores. You can find the formulas on the homework and exam pages.

April 19

Today in class I suggested a few rewiew problems, specifically numbers 2–4 from this old midterm. (In a couple cases I slightly altered the problem or gave hints.) I wouldn't ask you to calculate a slope field as complicated as the one in 1a (though 1b is fair), nor to solve a modeling problem like 5. If you want to discuss the solutions to any of these problems, or indeed any old exam problems you encounter, just write to me over the weekend. And I do recommend being comfortable with the homework problems.

About the quizzes: you should be able to see the answers to the closed quizzes by clicking the links on the calendar. If this doesn't work for you, let me know. Also, keep in mind that the quiz questions are significantly easier (on purpose) than what you can expect on the midterm. The midterm will generally not be harder than the homework, but it will be harder than the quizzes for sure.

April 16

We'll do one more quiz before the first midterm. Quiz 3 will open on Wednesday morning (10:30) and close Friday night (11PM). It covers some of the material from 2.6: it will ask you to determine whether several differential equations are exact. Like usual, the link will be on the calendar page.

April 13

You might enjoy this short video lesson by Nathan Grigg, 307 instructor extraordinaire, about phase lines and equilibrium solutions. In the video he discusses the exact same example we did in class on Friday. If you're unsure about using phase lines to figure out whether equilibrium solutions are stable or unstable, this will probably help you out a lot.

April 12

Quiz 2 is open: find a link on the calendar page. It's due at 9AM on Monday. It is a quick quiz about stable/unstable/semistable equilibrium solutions to autonomous differential equations (Section 2.5). The worksheet and its solutions are up on the materials page. Later today I'll post a solution to the last exercise from class, also on the materials page.

April 10

I posted my exams from the 307 class I taught last quarter under the "Exams" tab. Enjoy! Also, the second homework assignment is up, and it is due on the day of the first midterm exam.

April 8

Quiz 1 is open; there is a link on the calendar. It closes at 11PM tomorrow evening. The quizzes are intended to be quick and relatively easy; the tests will be harder. Think of the quizzes as a way to get a bit of practice with the definitions, and be sure you're keeping up.

April 7

The joint office hour schedule is up now. It is subject to change, so just check back before you go. They start tomorrow. Come with your questions and be prepared to work with your classmates: this is often a quicker way to get help if it's crowded. Have fun!

April 6

I hear that the bookstore is out of stock of the course textbook. I am really sorry about this situation. You do have a couple good options if you don't have a book yet. First, you can ask your 307 buddy. Second, you can look at the course reserves in Odegaard library: there are five copies there. Finally, you can come to the joint office hours starting on Monday (schedule to appear by the end of this weekend), and look at someone else's book there. My office hours will be 3-5 on Tuesday, and I will definitely bring my book.

April 5

The first online quiz will be next week, and I'll tell you about it on Monday. One question will ask for the name of your 307 buddy, a classmate whose contact information you have. Many of you found your buddy today in class. If you didn't, or if you're just joining the class, you'll have another chance on Monday.

April 1

The course syllabus is available here. Read it carefully. On Wednesday Professor Doug Lind will be substituting for class, and I will return on Friday. Office hours (TBA) will start next week. Also, no overloads for this class, and no registration after Sunday, 4/7.