changed office hours

Just for the next week I'll have office hours on Monday from 5 to 7 pm instead of Thursday from 10:30 to noon, so you can come to pick up your graded homeworks with the solutions. I'll have as usual office hours on Monday from 10:30 to noon as well, but I cannot give you the hws and the solutions at that time.

Turning in Late Homework

According to the policy set out on the Grading Page of the 21-260 Website, I accept late homework until the solutions are distributed. This typically happens during recitation six days after the due date.

Since Exam #1 will be held next Wednesday (You remembered Exam #1, right -- more on that later) graded homework and homework solutions will be distributed starting Monday afternoon. If you plan to turn in late homework, as some athletes do this week, you must turn it in to me by 1:20. You can give it to me during lecture, or put it in my mailbox.

How About a Cell Phone?

Someone left a cell phone in WEH 7500 after today's 12:30 lecture. If you are missing your phone, let me know. I'll hold onto it for a few days and if no one comes to claim it I'll sell it on ebay leave it with the information desk at the University Center.

Missing a Calculator?

I received this email from a student last week.

I am in Graph Theory in A51 after your class. A student left a calculator on (TI-83) one of the tables. If anybody asks, it has been turned into the UC info desk lost-and-found.

If you are missing a calculator, this may be yours.

Assignment for Week #4

The reading and homework for Week #4 have been posted. Follow the link from the Schedule Page of the course website.

UPDATE: You should feel free to use the program pplane wherever you are asked to sketch direction fields in a phase plane, or produce sketches of solution curves in the phase plane.

UPDATE: We did not get to cover linear independence of vectors this week, so I have removed problems 7.3.6 and 7.3.10 from the assignment. They will return on the next assignment, after next week's exam.

UPDATE: There is one other bit of information that will help with problem 7.2.22: If you have a matrix (or a vector) with entries that depend on t, then to differentiate that matrix (or vector) you simply differentiate each component separately.

For example the derivative, with respect to t, of [f(t) g(t)] is

[(df/dt) (dg/dt)].

I've asked your TA's to comment on this in tomorrows recitation.

Move Exam #3?

It has come to my attention that the Wednesday before Spring Carnival is an unpopular time to hold an exam.

It seems that it may be possible to move the exam to the preceeding Friday (Friday, April 13). Unfortunatly, there is nothing to be done about the whole 7:30 in the morning business. Unless I hear strong complaints about this change over the next few days, I will move the exam.

UPDATE: I will move Exam #3 to Friday, April 13.

The Blackboard Site is Available

I've made the Blackboard site available. It looks like all the grades for HW#1 have been recorded, as well as some grades for HW#2. For news and information about the course, you should check the course website, or this Blog. I'll try to keep them both updated. The Blackboard site will mainly be there for you to check your grades.

Assignment for Week #3

The reading and homework for Week #2 have been posted. Follow the link from the Schedule Page of the course website.

There are a couple "homemade" problems this week. They are available in a pdf file linked from the assignment page. You only need to complete the first two (this week). Early next week I'll post a new pdf file with only those problems you need to complete.

UPDATE: For problem 2.3.15 you will want to use dfield, or some other technology. You will find it quite difficult to complete the integration by hand. Additionally, problem 2.5.7(b) makes some comments about the phase line for the differential equation in question. You should actually show the phase line in your solution. Problem 2.5.20(b) is also simplified greatly by looking at the phase line, though it is not, strictly speaking, necessary.

Problem 2.3.8

I've been asked to comment on problem 2.3.8, in which you are asked to find the rate of return required for an investment of $2000 per year to grow to $1,000,000 over the course of 40 years. To complete this problem, as noted by commenter "anonymous" to this post, you must solve an equation of the form (e^(rt)-1)/r=[constant].

I didn't remark on this earlier, because I though commenter Jeffrey addresses the situation adequately. You will have to find some way to solve this numerically. If your calculator has a "solver" you can use that. Another method would be to graph the function f(r)=(e^(rt)-1)/r-[constant] and determine (by inspection) where it crosses the x-axis. Newton's method could, in principle, be employed, but it gets unwieldy rather quickly.

Sections A & B

Some of you have not collected your graded homework from last week and/or solutions of Homework 1 . Please stop by my office to collect these. I won't be carrying them to class next week.

Office Hours for Dr. Handron

This semester, starting tomorrow, I'll hold regular office hours on Tuesdays, from 10:30-12:20, and on Wednesdays, from 1:30-3:20. I'll be in my office during those times, and you can see me to discuss any aspect of the course (homework, previous grades, etc.)

Assignment for Week #2

The reading and homework for Week #2 have been posted. Follow the link from the Schedule Page of the course website.

A number of the problems will require you to use some sort of computer technology. I would recommend the Java applet dfield, which I will be demonstrating in class on Monday and/or Wednesday.

UPDATE: I've made a slight modification to the homework exercises for Week #2. I've removed 1.1.27 and 2.1.15 from the assignment, and added 1.2.16, 2.3.4 and 2.3.8.

UPDATE: I've also removed 2.2.22, and added 2.3.6.

Office Hours for sections F and G

Office hours for Sections F and G are Tuesdays 3:30 to 5:00 and Wednesdays 1:00 to 2:00. My office is in the Physical Plant Building, please follow the directions to find it.

Information for Sections A & B

My office is WeH 7215. It was listed incorrectly on the course website. My office hours are Tuesdays 1:30 p.m. to 3 p.m. and Thursdays 11 a.m. to 12:30 p.m.

Our Textbook is Sold Out

I have heard from a few students that the CMU Bookstore has run out of our textbook. You may all rest assured that I have anticipated just such an occurrence. The homework problems are conveniently available as a pdf file. I won't do that every week, but I know this is a common problem in the first week.

Incidentally, if you are sans textbook, and would like a reference while you complete the homework, you can use the lecture notes I posted earlier.

Textbooks, Old and New

Some students have asked about using the 7th edition of our textbook, rather than the current 8th edition. To my knowledge, there are no major changes to the text. There are a few changes, though. If you plan to use the 7th edition, you will want to pay careful attention to the exercises, or you might end up doing the wrong problems.

For instance, this week, the problems 1.3.2, 1.3.10, and 1.3.27 are the same. The 7th edition does not have a problem 1.3.30, though.

If you do decide to get by with the 7th edition, you will be responsible for making sure you do the correct problems. If you fail to do so, and points are deducted, well... don't come cryin' ta me.

Office Hours for Week #1

I'll hold office hours tomorrow (Thursday) from 1:30-3:20. At the start of next week I'll announce my regular office hours for the semester.

Class Schedule for Wednesday

Since Lecture 2 (12:30) did not meet on Monday, due to the half-holiday, I'm going to cancel the 10:30 (Lecture 1) lecture on Wednesday. This will make sure that the two lectures stay on the same schedule.

I announced this at the end of class yesterday, but I want to make sure the word gets out.

Assignment for Week #1

The reading and homework assignments for Week #1 have been posted. Follow the link from the Schedule Page of the course website. You will have to take a short tour of the Policies page before you can view the Exercises.

The assignment for this week should not be especially strenuous. If you have any questions or concerns, though, I encourage you to post a comment under this entry. Your TA's and I will try to review the comments and respond as needed. Probably not at 2:00am, though.

Alternatively, if you see a question you feel like answering, you can go ahead and do that too.

UPDATE: I've corrected the pdf file to correct the typo in problem 1.3.2. I've also corrected the due date in the pdf file: Friday 19 January.

Lecture Notes for Weeks #1 and #2

During the first few weeks of the semester we will be jumping aroung in the textbook quite a bit. In order to give a more coherent presentation, I've written up these notes. They are definitely "rough around the edges," but I think they will be useful, especially to read over after attending the lectures.

UPDATE: I've corrected the link to the notes. They should download correctly now.