Example: Linear Difference Equations (Speedy Car Rental)
                                                       xxx
          Washington University in St. Louis

Math 309, Matrix Algebra
Section 1, Fall 2008
 
Note:  Math 309, Sections 1 and 2 (taught by ESE) use the same textbook and will cover nearly the same "core topics." These make up most of the course.  The sections may vary a bit in emphasis and in the selection of a few optional topics. 

This syllabus applies only to Section 1 .


Instructor:          Professor Ron Freiwald 

Office:               Cupples I, Room 203A, 935-6737
Office Hours      Revised for the days up until the final:

Wednesday, December 10:  1:30 (or very soon thereafter) - 3
Thursday, December 11:      2:30-4
Friday, December 12:          2:30-2:00
Monday, December 15:       10:30-12


Class Meeting
  M-W-F 10-11 a.m.
Classroom         Cupples I, Room 113

                                                                  Course Bulletin Board


The final exam (F) will be held at the time scheduled in the Course Listings book:
Tuesday, December 16, 2008, 10:30-12:30 in the regular classroom: Cupples I, Room 113
Information about the final exam

All unclaimed graded homeworks (including the most recent HW 12), quizzes, and exams are in a folder on the counter in the Math Office (Cupples I, room 100).  Ask the receptionist for assistance if needed.
Please claim anything you want:   I will hold any unclaimed papers, and the graded final exams, until the end of January, at which time they will all be discarded,  

Online Course Evaluations
for most courses should go live on Friday, November 21, and they will remain open through Friday, December 11."   Please take the time somewhere in that period to fill out a course evaluation.  Evaluations are helpful to instructors in planning future version of the course and they are helpful to other students in learning something about past reactions to a course/instructor.
Math 309 Scores: homework, quizzes and all exams (12/19/08)


"What is written without effort is in general read without pleasure."  
                                                   Samuel Johnson (1709-1784)

Homework Due Date/Reading
Problems to Hand In
Other Recommended Problems (not to hand in)
Handouts &
Solutions
 

Read Section 6.6

Read 7.1 (We covered most of this in class in the final lecture. You can skip the couple of paragraphs about the spectral decomposition, although we'd certainly have talked about that if we'd had time.)

We also introduced the material in 7.2 -- it would be good to read 7.2 but it won't be on the final.  .
No more problems to hand in.  But you should do the recommended problems in preparation for the final exam.

Sec 6.6:  7a, 8a, 9, 10a
Sec 7.1:  3,5,7,9,19,25(a,b,c),26



        OLDER STUFF
              BELOW

Quiz in class Friday, 12/5

HW 12, due in class  Friday, 12/5.  This is the last "hand-in homework.  I will suggest some addition problems to practice with the material beyond what's on HW 12.


Section 6.3 was finished in class Monday, 11/24.  Please be "up-to-date" on that after reak.

Read Sec 6.4 (you can skip the last section on QR factorization)

Read Sec 6.5 (you can skip Theorem 15, p. 414 ))
Always include enough or explanation or calculation in every homework solution so the reader can understand how you got your answer.

Sec 6.2: 10,14, 20, 28
Sec 6.3: 10, 12, 20, 24
Sec 6.4: 4,10
Sec 6.5: 4,6,10,14
Sec 6.6: 4
Sec 6.2:  9,13,15, 23,24
Sec 6.3:  9,11,19, 21,22
Sec 6.4:  17,18
Sec 6.5:  3,5,9,13,17,18
Notes on the Gram Schmidt Process



Optional Exam 3: Solutions

Homework 12 Solutions
HW 11 due in class on Friday, 11/24

Read Sec 5.5

Read Sec 5.6.  You can skip the couple of paragraphs about "Change of Variable" if you like.

Skip Sec 5.7 - 5.8

Read Sec 6.1-6.3
Always include enough or explanation or calculation in every homework solution so the reader can understand how you got your answer.

Sec 5.5:  6,10,12,18
Sec 5.6:  2, 4, 6  (find a nonzero value of p)
Sec 6.1:  4,6,12,18,24,28
Sec 5.5:  5,9,11,15
Sec 5.6:  5
Sec 6.1:  5,7,19,20
Simple example illustrating the ideas of Section 5.5

Proofs of the results in Section 5.5

Another Example with a 2x2 Real Matrix with Complex Eigenvalues

The Spotted Owls

Homework 11 Solutions
Quiz in Class on Friday, 11/14
covering 5.1-5.3

Read Sec. 5.3-5.4-5.5
Read Appendix B  (pp. A3-A8) with as much care as needed for a review of complex numbers)

HW 10 due in class Friday, 11/14 -- problems to be posted soon.
Always include enough or explanation or calculation in every homework solution so the reader can understand how you got your answer.

Sec 5.3: 4,6,10,14,24,26
(for # 14): notice that, to save you time, the eigenvalues are given in the text in a paragraph immediately following Exercise 6)

Sec 5.4:  4,10,14,22, 26 (look back at #25 for the definition of "trace."  You may use anything stated in #25 if it's helpful.)
Sec 5.3:  3,5,13,21,22,23,25
Sec 5.4:  3,9,13,23
Relation among dimension of eigenspaces, multiplicity of eigenvalues and diagonalization

Theorem 7, p. 324: Error in Textbook

Matrices for Linear Transformations: Examples



Homework 10 Solutions
Exam 2 in class Friday, November 7 (see information above)

Because of the test, HW 9 will be due in class on Monday, 11/10

Read 5.1 - 5.2 (a lot in 5.2 is material we already covered on determinants -- but a good brush-up review of the basics)
Always include enough or explanation or calculation in every homework solution so the reader can understand how you got your answer.

Sec 4.6:  4,8,10,16,22

Do this Supplementary Problem on Markov Processes

Sec 5.1:  14,18,24,26,
Sec 5.2:  8,14,18
Sec 4.6: 3,6,9,11,17,18
Sec 5.1: 5,7,13,17,21,22,27
Sec 5.2:  7,13
Examples of Calculations for Eigenvalues and Eigenspaces, Diagonalization

Another Diagonalization Example

Theorems about linearly independent eigenvectors

Homework 9 Solutions

Exam 2 Solutions

Math 309 Scores, including Exam 2
Read Sec 4.5- 4.6 
Be sure you've read all the supplementary handouts from last week.

Skip Sections 4.7-4.8
Read 4.9 and related handout on Markov Processes

HW 8, due in class on Friday, October 31

Exam 2 in class Friday of NEXT week (November 7)
Always include enough or explanation or calculation in every homework solution so the reader can understand how you got your answer.

Sec 4.4: 12,20,30
Sec 4.5:  6,8,12,22

Do the Supplementary Problems here on Diagonalization

Do the Supplementary Problem here on Rotation of Axes
S
Sec 4.4: 15,16,31
Sec 4.5:  5,15,19,20,29,30
Invertible Matrix Theorem, Updated Section 4.6

Introduction to Markov Processes

Homework 8 Solutions
Items in this row cover MW of Fall Break Week + the week after Fall Break. 

Because of Fall Break, HW 7 is due Friday, October 24--so it'll be a bit onger than usual.

Friday, October 24 is also a QUIZ day.

Read 4.1 - 4.4 and handout notes on diagonalization
Always include enough or explanation or calculation in every homework solution so the reader can understand how you got your answer.


Sec 4.1: 2,6,16,18,22
Sec 4.2: 4,10,12, 16,18,24,28,32
Sec 4.3: 8,14,16,20,26, 32
(#32 should also assume that "T is linear")
Sec 4.4: 4,8,14
Sec 4.1: 5,17, 23,24,31
Sec 4.2: 5,23,25,26
Sec 4.3: 1,3,5,11,21,22,29,30,33
Sec 4.4: 3,7,13
Class handout about Nul A and Col A

Two Examples about Bases

Example: Basis for Col A and Nul A

Example: A Nonstandard basis for the plane

Example: The isomorphism between P3 and R4

Introduction to Diagonalization

Supplementary Example: Rotation of Axes

Homework 7 Solutions
HW 6  Due in class Friday, October 10

Read Sec 3.2.
In Sec 3.3, skip up to "Determinants as Area or Volume" and read from there to the end of the section. You might want to just quickly scan the earlier material, and the "Numerical Note" about the skipped material on Cramer's Rule.

Read Section 4.1
Always include enough or explanation or calculation in every homework solution so the reader can understand how you got your answer.

Sec 3.1: 18 (read paragraph preceding exercise)
Sec 3.2: 8,12,16,18,20,24,
34,36,40(c,d,e)
Sec 3.3:  Do the two problems on this supplementary sheet and then also 30,32
Sec 3.1: 15,39,40
Sec 3.2:  7,11,21,27,28,31
Sec 3.3:  21,23,31
Exam 1 Solutions

Math 309 Scores, including Exam 1

Homework 6 Solutions
HW 5
Due in class Friday,
October 3


Skip Sec. 2.5, 2.7
(you might be interested in a quick read of 2.7 if you're in computer science; and perhaps 2.5 if you're in EE --although in 2.5, the algebra leading up to the example it a bit harder to read.)

Read Sec 2.6 (and Notes on 2.6); read Sec 3.1

EXAM 1: IN CLASS MONDAY, OCT. 6
NO QUIZ THIS FRIDAY
Always include enough or explanation or calculation in every homework solution so the reader can understand how you got your answer.

Sec 2.3 (Note the opening sentence at the start of these exercises :  "Unless otherwise stated, assume...") :  
6,16, 22,24,26,34,38

Sec 2.4:  4,6 (assume all blocks are square)
              10 ("find X,Y,Z"  means "find X,Y,Z in terms of A,B,C")

Sec 2.6:  2,6,8

Sec 3.1:  2, 8, 20, 22
Sec 2.3: 3,7,11,12,13,23,29
Sec 2.4: 1,3,7
Sec 2.6: 3
Sec 3.1: 1,7,19,21
Notes on Section 2.6: Leontief Open Economy Model

Leontief Example with Real Data

Elementary Matrices, EROs, and Determinants

Homework 5 Solutions


HW 4
Due in class Friday, September 26


Complete reading
Sec. 2.1-2.3
Read Sec. 2.4 (in this one section, I'm mainly interested in the mechanical stuff)
Always include enough or explanation or calculation in every homework solution so the reader can understand how you got your answer.

Sec 1.9:  18, 28, 30
Sec 1.10:  10
Sec 2.1:  6,12,18,20,22,28
Sec 2.2:  6, 8,16,18,20,
              22,24,30,32,38
Sec. 1.9:  15,23,24,35
Sec 1.10:  9
Sec 2.1:  5, 9,11,15,16
Sec 2.2:  9,10,13,15,31,33
Linear Difference Equation Example (Speedy Car Rental)

Matrix Multiplication Examples

The Transpose Theorem

Effect of Elementary Matrices

The Invertible Matrix Theorem (my presentation chart)

Homework 4 Solutions
HW 3
Due in class Friday, September 19

Read Sec 1.7-1.8-1.9
Read Example of Difference Equations in Sec 1.10.
Start reading Sec 2.1

Quiz in class, Friday, September 19.
Always include enough detail in every homework solution so the reader can understand how you got your answer.

Sec 1.5: 14,16,18,22,28,36
Sec 1.7: 12,24,28,38
Sec 1.8:  6,12,18,24,32,34
Sec 1.9:  4,6,8,10,12
Sec 1.5:  13,17,19,23,24,
26,31,37

Sec 1.7:  13,17,19,21,22,25
Sec 1.8:  5,9,13,16,21,22,27,31
Sec 1.9:  3,5,11
Summary Sheet on Linear Transformations and Matrices for Sections 1.8-1.9



Homework 3 Solutions
HW 2: Due in class Friday, September 12

Read Sec. 1.4
Read Sec. 1.5
Read Sec. 1.6
Start reading Sec 1.7
Always include enough detail in every homework solution so the reader can understand how you got your answer.

Sec 1.3:  10, 16, 18, 26
Sec 1.6:  14
Sec 1.4:  6,16,20,22,28,34
Sec 1.5:  4,6,12
Sec 1.3: 23, 24
Sec 1.6: 13
Sec 1.4:  7,13,23,24,26,35
Sec 1.5:  3,5
Extra Example (Wednesday lecture)
Similar to class example, but there are some comments near the end that are important to read.

Homework 2 Solutions

Hand-in Homework 1 due in class Friday, September 5

Be sure to read How to Study Linear Algebra at this link OR in your Study Guide.

Read Note to Students on pp. xxxv-xxxvi

Be sure to read the Introductory Example
(about Leontief) at the start of Chapter 1.

Read Sections 1.1-1.3

Read Section 1.6

Note: Quiz in class Friday, Sept. 5
Sec 1.1:  16,  20, 28, 34 (this requires doing 33 first: check answer to 33 in the back of the text before doing 34)




Sec 1.2: 10, 14, 16(b),18, 30 (refer back to #29)

Sec 1.3: 8, 12, 14

Sec 1.1:  1,5,7,13,15,
23,24,27,25,33

Note: nearly every section contains  exercises (like #23, 24) with a list of true/false questions.  You should always do those, even if I don't mention the problem here.

Sec 1.2:  3,13,15, 19, 21, 22, 23,
27, 29, 31

Sec 1.3:  5,7, 11,13


Example: Closed Exchange Economy

Practice Sheet

Solutions for Quiz 1

Homework 1 Solutions

Textbook & Related Resources
Linear Algebra and Its Applications, by David Lay.  This text is very well-written and is a must-read as the course moves along. 

A copy of the author's Study Guide should be bundled with your textbook at the Campus Bookstore. The Study Guide is a very valuable resource.  I recommend that you consistently use it as you work your way through the course. In particular, read carefully the note on How to Study Linear Algebra at the beginning of the Study Guide.  If you are purchasing your books through a different source, the Study Guide, though very useful, is optional.

There is some good supplementary material at the Companion Web Site for the course (http://www.laylinalgebra.com/).  In particular, there's a large collection review sheets and practice exams from the author.  (The practice exams may or may not be what our exams look like, but they certainly provide a good self-test on some of the material.)

You can also look at whatever material is available at MyMathLab: registration material should be included with the textbook.
Homework

Each  week I will post here a list of homework exercises to be handed in.  These assignments will normally be due in class on Fridays (HW 1 is due on Friday, September 5).  Late homeworks will not be accepted unless there is a legitimate special reason such as illness.   When the problem set is first posted on this page it may not be complete; I often add to the problems for the coming week as the lectures go by.  However, the list of problems that will be due on Friday will always be complete by noon on the preceding Tuesday.  Be sure to check after Tuesday noon to be sure that you have the complete set of problems due on Friday.

There will also be a list of recommended problems, not to be handed inYou should be sure you can do them all and try some others from the text book as well.

The hand-in homeworks should be written up on 8.5 x 11 paper with "clean edges" (not torn out from a spiral bound notebook). 
  • One goal in most upper level math courses is to develop clear writing and arguments, so the solution of each problem should be written up very clearly and legibly.  For the sake of the grader, be sure your writing is dark enough to be read easily.
  • Solve problems first on scratchpaper; the use the scratchwork to write your hand-in solution.  The reader should never feel like s/he is reading your scratchwork.
  • Write your solutions (calculations, proofs) as if the intended reader were an average student in the class.
  • Check your mathematical style by reading aloud the words and symbols you wrote, exactly as written.  What you hear should be smooth-sounding English -- or else something is missing on paper!
  • If necessary, rewrite the solution until you think it says what you want to say in a way that's clear and easy to read.
                   "What is written without effort is in general read without pleasure."  
                                                                      Samuel Johnson (1709-1784)

Do you really want an unhappy reader evaluating your work?  

Talking with other students about homework problems is a very good way to learn and is encouraged: BUT each student must write up his or her own homework.  Therefore, no solutions from two students should look too much alike.  After all, everybody says things in a unique way, makes up notation as needed, etc.  A good way to avoid "copying" even inadvertently from another student is to talk about problems together without taking any notes away from the conversation.  This lets you share understanding and ideas, but forces you to reconstruct your own understanding on paper.  In case of any doubts, ask me.

A grader will assign a score to each homework.  At the end of the course, the scores will be converted to percents.  Then the lowest two scores will be dropped and the average of the remaining scores will be your homework score, H.

Quizzes
 

On alternate Fridays (beginning on September 5) there will be a short quiz, about 15 minutes long, given at the end of the class.

In this alternating quiz schedule, the weeks in which we don't have 3 lectures -- because of a holiday or in-class exam -- won't count.  This means that there will be only be 5 or 6 quizzes during the semester. 


The quizzes will contain one or more questions requiring you to do a very simple calculation, interpret a calculation, give a definition, state a theorem, or answer some true/false questions.  There will be no make-up quizzes.  The quiz scores will be rescaled as a %, and the lowest score dropped.  The remaining scores will be averaged together to produce your quiz score, Q.

Tests 
There will be two exams (E1, E2) in class during the semester.  The dates of these exams will be announced at least 1 week in advance, but the dates will probably be near the end of September and near the end of October. 
          There will be an optional Exam 3 (E3) given in the late afternoon or evening, probably shortly after Thanksgiving Break.  
          (See details below under "Grading.")


          The final exam (F) will be held at the time scheduled in the Course Listings book:
Tuesday, December 16, 2007, 10:30-12:30 in the regular classroom: Cupples I, Room 113
          Information about each exam, when it's ready, will be posted on this web page.

Course Grade

        
Your grade will be based your Total Score (%) T, computed as follows:

1) if you do not take the optional Exam 3:  T = (1/5) * (E1 + E2 + F + Q + H )
(2 exams, final, quizzes and homework scores are all equally weighted)

2) if you do take the optional Exam 3, then your T will be the larger of

                         T = (2/11) * (E1 + E2 + F + Q + H) + (1/11) * E3

                         T = (2/12) * (E1 + E2 + E3 + F + Q + H )

(If you choose to take E3, you have to take it seriously:  the score will count, and it could hurt your T value. However if E3 doesn't go well, it will carry only half the weight of the other exams;  if it helps you, it will carry the equal weight with the other exams). 
I will base course letter-grades on the number T, rounded to the nearest integer.  I will not make up a grading scale until the end of the course, but it is guaranteed that the grading will be no more severe than
                                    90-100   A  (possibly +/-)
                                    80-89     B  (possibly +/-)
                                    65-79     C  (possibly +/-)
                                    50-64     D
                                     < 50      F
           If you are taking the course with a pass/fail grading option, then you will need a T score value equivalent to a C- or better to
           earn a "pass."

If any student has signed up officially to audit the course, then s/he should talk with me about the requirements to receive the "grade" of "successful audit."


Course Evaluations   Online Course Evaluations will be available toward the end of the semester.  I urge all of you to participate.  Good feedback is valuable to me and to your fellow students.

Academic Integrity  This link gives the general policies of the University on academic integrity.  Please also see the comments, above, about homework collaboration.

Anonymous Feedback to Professor Freiwald.  Of course, I'd really prefer open feedback and discussion about the course at any time.  However, this link is provided as a way for students to offer suggestions and comments anonymously.  I'll keep this link here as long as it's constructively used.
  (I can't respond, of course, to your anonymous e-mail.)