Spring 2018

Harvard Extension School

Mathematics E-21b - Spring 2018

Linear Algebra

Instructor:
Robert Winters

Course Assistants:
Jeremy Marcq
Renée Chipman

Handy Links:

Calendar of topics and
homework assignments

Linear Algebra Toolkit

Math E-21b syllabus

Solutions
requires username/password

Canvas Site


Recommended Course Textbook

Linear Algebra with Applications, 4th Edition
by Otto Bretscher

ISBN: 0136-00926-3
ISBN 13: 978-0136-00926-9
Publisher: Prentice Hall

Bretscher, 4th Edition

Compare prices:
Linear Algebra With
Applications, 4th Ed.

OR

Linear Algebra with Applications, 3rd Edition
by Otto Bretscher

ISBN: 0131-45334-3
ISBN 13: 978-0131-45334-0
Publisher: Prentice Hall
Bretscher, 3rd Edition

Compare prices:
Linear Algebra With
Applications, 3rd Ed.

OR

Linear Algebra with Applications, 5th Edition
by Otto Bretscher

ISBN: 0321-79697-7
ISBN 13: 978-0321-79697-4
Publisher: Prentice Hall
Bretscher, 5th Edition

Compare prices:
Linear Algebra With
Applications, 5th Ed.

 
The older 2nd edition of the text may also be used. The material is fundamentally the same in all editions and all homework assignments will be made available as printable PDFs. Additional supplements on various topics in differential equations will also be made available during the course.

A key matching HW exercises in different editions is available on request.

A copy of the text will be put on reserve in the Grossman Library in Sever Hall.


Go for a Walk

AMC Local Walks:
http://amcboston.org/walks


 

Announcements:

Course grades will be available online (not via Canvas) on Tuesday, May 22.
Final exam scores are posted on Canvas. Approximate letter grades are shown below.

Approximate letter grades for Exam #1
Total points on exam was 50. Median score was 41.0.
Mean score was 39.3. Standard deviation was 9.3.
Scores are posted on the Canvas site.
score grade   score grade
45+ A 30+ C+
42+ A– 27+ C
39+ B+ 25+ C–
36+ B 23+ D
33+ B– 0-22 E
Practice Exam #1     Solutions
Exam #1 solutions
 
Approximate letter grades for Exam #2
Total points on exam was 50. Median score was 42.0.
Mean score was 39.0. Standard deviation was 9.2.
Scores are posted on the Canvas site.
score grade   score grade
45+ A 30+ C+
42+ A– 27+ C
39+ B+ 25+ C–
36+ B 23+ D
33+ B– 0-22 E
Practice Exam #2     Solutions
Exam #2 solutions
Approximate letter grades for Final Exam
Total points on exam was 80. Median score was 59.
Mean score was 55.5. Standard deviation was 15.5.
Scores are posted on the Canvas site.
score grade   score grade
70+ A 48+ C+
65+ A– 44+ C
60+ B+ 40+ C–
56+ B 37+ D
52+ B– 0-36 E
Practice Final Exam    Solutions

 

HW #14: Read sections 9.1 and 9.2 and the supplement on nonlinear systems and linearization. There are five problems in the nonlinear supplement and solutions are posted for those problems. There is no assignment to be turned in.

The Final Exam will take place on Thursday, May 10 from 7:40pm to 9:40pm in Emerson 105 (not our usual lecture hall).

Practice Final Exam    Solutions


HW #13 problems (due in class on Thurs, May 3 or online by Sat, May 5, 11:59pm EDT)

Though there are no prepared Lecture #13 notes, all of the necessary information is in sections 9.1-9.2 of the text and in the following supplements:

First order linear systems of differential equations and evolution matrices

Sampler of Phase Plane diagrams for uncoupled, coupled, period, and stable sink linear systems and a nonlinear system

Matrix Methods for Solving Systems of 1st Order Linear Differential Equations

You may also want to make use of the following java-based [pplane] tool for showing vector fields and flows: http://math.rice.edu/~dfield/dfpp.html. The current version requires you to download a Java executable file to your own computer and to run it locally on your own machine. You can customize various options. You can also print the graphs.


HW #12 problems (due in class on Thurs, Apr 26 or online by Sat, Apr 28, 11:59pm EDT)

There are no prepared Lecture #12 notes yet, but all of the necessary information is in the Lecture #11 Notes and the appropriate sections of the text on quadratic forms.


HW #11 problems (due in class on Thurs, Apr 19 or online by Sat, Apr 21, 11:59pm EDT)

Lecture #11 notes


HW #10 problems (due in class on Thurs, Apr 12 or online by Sat, Apr 14, 11:59pm EDT)

Lecture #10 notes


HW #9 problems (due in class on Thurs, Apr 5 or online by Sat, Apr 7, 11:59pm EDT)

Lecture #9 notes


Plan ahead: The exam dates for this course are March 1 (~70 minute midterm during latter part of class), April 19 (~70 minute midterm during latter part of class), and May 10 (2 hour Final Exam). Most students who can take exams in person will do so on the scheduled date of the exam. Distance students are responsible for finding a qualified proctor near their home who will administer and monitor them throughout the duration of their exam. Students can find more information at the Extension School website here: https://www.extension.harvard.edu/exams-online-courses


A student information questionnaire is now posted on the Canvas site. Though this is completely optional, we would appreciate your completing the survey.

A message was sent to the entire class list on Feb 10 with information about accessing homework solutions. Practice exams and exam solutions will also be found in that same directory when the time is right. If you did not receive the message, (a) check your Spam filter or (b) let me know via email and we'll figure it out. - RW


We prefer that assignments be submitted on paper for those who attend class in person. Other students should submit their assignments as a single scanned PDF file, but this option is also open to local students for any given assignment.

A basic standard is that you should not scan at resolution greater than about 120dpi. Anything beyond that is not necessary for handwritten work and dramatically increases file size. Black & White scans are preferred unless there is a good reason to scan using color. Please also make sure that the contrast is adjusted properly so that all work is clearly legible.

Photographs of assignments will not be accepted - scans only.

Based on class size and practical limits, we will select a subset of each assignment for grading. Solutions to all problems will be posted after the due date.


We are offering this course this semester for the first time with an online option. Some details are being worked out as we go, so check back frequently on this site and on the Canvas site for the course.

Note: The "Graduate" credit option is primarily for students enrolled in certain Extension School graduate programs such as the "Math for Teaching" program. All other students (including high school students) should register for the "Undergraduate" option or the Noncredit option (if you will not be submitting homework or taking exams).


Math E-21b Course Information and Syllabus (Spring 2018)       PDF version (Spring 2018)

Classes will meet every Thursday evening from 7:40pm to 9:40pm in Harvard Hall 201 (next to Johnson Gate) starting January 25. There will also be an optional weekly problem sessions (conducted by TAs Jeremy Marcq and Renée Chipman) at days and times and locations to be determined. TA Renée Chipman will also meet with individuals and small groups on request. Students are not assigned to sections - any student may attend (in person or online) the sessions by either Jeremy, Renée, or both.

Jeremy's weekly section is scheduled for Tuesdays from 7:40pm to 8:40pm in Maxwell Dworkin G125.

Each week on Thursday evening before class (starting February 1) there will also be an optional pre-class Q&A session starting at 6:40pm (or soon thereafter) - also in Harvard Hall 201. The primary purpose of this Q&A session will be to take last-minute questions on the assigned homework problems after you have struggled with them. Robert Winters will conduct the session.

Important Dates - Harvard University Extension School - Spring 2018

Registration ends Sun, Jan 21
Late registration (with $50 late fee) Mon, Jan 22 - Mon, Jan 29
Course and credit status changes deadline Mon, Jan 29
Course drop deadline for full-tuition refund Mon, Jan 29
Course drop deadline for half-tuition refund   Mon, Feb 5
Withdrawal for WD/WN grade deadline (no refund)     Fri, Apr 20
Final Exam Thurs, May 10
Grades available online Tues, May 22

Questions, questions, questions..... and some answers

1) All of the lectures will be recorded and made available within about one day. I don't believe there is any capability for live streaming. All of the lectures will be available via a link on the course's Canvas site for the duration of the course and for a few weeks thereafter.

2) People who attend class in person can submit HW on paper in class. Distance students will be able to submit HW as a single scanned PDF (easily readable and with a reasonable file size, i.e. not scanned at an unnecessarily high resolution). Since classes are on Thursday and the recorded lectures are available on Friday (usually), I generally have assignments due no later than the following Friday or Saturday. All students have the option to submit their assignments online, including those who regularly attend the lectures.

3) Exams for Distance students are handled via the Exams Office. Distance students have to make arrangements for a proctor and this must be approved by the Exams Office. Proctors scan and send the completed exams to the Exams Office, and they then make them available to me for grading. We will have two midterm exams and a final exam. The Calendar is given at: http://math.rwinters.com/E21b/calendar.htm

4) I usually post announcements and assignments initially on this site: http://math.rwinters.com/E21b/
I also then post them on the Canvas site which is linked from this site, but it's best to first check on this (non-Canvas) site.

5) The main materials of the course are the lectures, my weekly Lecture Notes, and the Bretscher text (best to get an inexpensive one online - links for best deals on the course website), and, of course, the homework assignments.

6) Most students who can take exams in person will do so on the scheduled date of the exam. Distance students are responsible for finding a qualified proctor near their home who will administer and monitor them throughout the duration of their exam. Students can find more information at the Extension School website here: https://www.extension.harvard.edu/exams-online-courses

Since Linear Algebra is largely independent of the Calculus sequence, any prerequisites other than general mathematical competence are really just recommendations or suggestions. Even the Placement Test is really for your own use to see if you're ready for the course. It is most certainly not required for registration.


Homework deadlines: All homework is due in class the week after it is assigned - either a) in class or b) in the dropbox marked "Math E-21b" (may still be marked E-21a) on the second floor of the Science Center by 9:40pm the day it is due, or c) online via the Canvas site - typically by 11:59pm on the Saturday after the following lecture. Late assignments will generally not be accepted unless cleared in advance with either one of the Teaching Assistants (who will be doing the grading) or the Instructor. Your lowest homework grade will not factor into your course grade. No credit will be given after solutions have been posted.

Homework policies: Please write up your solutions neatly and show all work. If you use a calculator or other technology as part of your solution, this should be clearly indicated. When asked to "prove" or "justify" a statement, you must write clear verbal explanations in addition to doing out the math; the idea behind a proof is to convince the reader that the statement is true. Most problems will be marked out of 5 points (with the exception of some longer problems, which may be 10 points).

Guidelines: Please 1) staple all your pages; 2) write the assignment number on the top; and 3) include your name.

Completeness: It is always best to attempt every problem and to turn in each homework assignment even if there are some errors or omissions. Please always include work you have done that led to the final solution; this way we can point out where you have made an error. However, please don't include pages and pages of extraneous work. Your work will be graded on quality and not by weight or the number of pages submitted.

Collecting and Returning: We will collect homework submitted on paper each week at the lecture. Graded homework will usually be available before and after class. Homework assignments submitted online will generally be graded with only minimal comment, so you should consult the posted solutions to better understand whatevererrors you may have made.

If there are any questions on these policies, please let us know. We look forward to working with you all!

Birds on a wire

Homework: Total points and median scores

HW #1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13
Total Points 50 50 50 50 50 50 50 50 50 50 50 50 50
Median Score 47 48 45 46 47 48 45 48 47 47 46.5 47 --
Mean Score 41.8 43.9 41.1 41.5 39.9 43.0 36.8 42.7 39.1 39.8 40.3 40.4 --

Academic Integrity Letter from Robert Neugeboren, Dean of Students, Harvard Extension School (2014)
In particular: All work submitted ... must be your own words and ideas, or the source must be clearly acknowledged. Copying material from public websites (or other sources) ... is plagiarism, unless the source is properly cited ....



Harvard Hall - This is where class meets (from a 1910 postcard - 100 years ago).

Restore America's competitiveness!
Don't forget to pick up a textbook!

A letter to the New England Courant, dated May 14, 1722, and actually written by Benjamin Franklin under the
pseudonym "Silence Dogood." This was one of 14 letters by Silence Dogood and concerns Harvard University.

with the permission of Bill Griffith

posted with the permission of Bill Griffith

A word about calculators:

Though you can do this course without a matrix-capable calculator or mathematical software, it's certainly easier if you have an electronic servant to handle the drudge work. I use a TI-85 (no longer sold, but a good buy if you can find a used one) and I've been very happy with it. Ideally, you'll want a calculator that can find the reduced row echelon form of a matrix (RREF). You might also want one that can calculate determinants, eigenvalues, and eigenvectors, but that's a lesser priority. The TI-83 Plus, the TI-84 Plus, the TI-84 Plus Silver Edition, the TI-86 (also discontinued), and the TI-89 calculators can handle these operations. You don't need anything fancier than this.

One feature that I find very handy is the ability to display fractions and convert a decimal expression (for a rational number) to a fraction. That's useful when translating the results of an RREF calculation into parametric equations for a solution to a system of linear equations.

Here's a link that gives a comparison of the various TI calculators. Other manufactures also produce calculators that will work well with this course.

Linear Algebra Toolkit - an excellent online collection of tools that will not only do the calculations but also walk you through the steps. (The PERL scripts are written by Przemyslaw Bogacki.)

Useful Links:


Download your free Adobe Acrobat Reader for reading and printing PDF formatted documents.

Please send comments to Robert Winters.

URL: http://math.rwinters.com/E21b

Last modified: Wednesday, May 16, 2018 5:51 PM