Linear Algebra

All reading assignments, problem sets, and so forth will be posted on this page. Please check here at least every Tuesday to collect the readings and problem sets. Also, you'll find other handouts, class "news" updates, and Maple instructions.



The old linear algebra page (last year's class) is here. If you're using Mathematica, you'll find Mathematica instructions on this page. Remember, I don't mind if you use Mathematica and will try to help you with it, but it is "unsupported".


News:

The midterm synthesis assignment is now ready! Please note the conditions: you must do this assignment consulting only your brain, your class notes, and our textbook. Do not use any outside sources. There is a hand-drawn picture for Q1, obviously missing from the computer file; I've placed a paper copy in your mailboxes.


Readings and Assignments:

Remember to collect readings on Tuesdays, finish the readings by Friday, and complete the homeworks by the following Tuesday.

March 5-12: Reading I: Sections 1.1-1.2, Assignment 1
There are some pictures accompanying Assignment 1; I've put copies in your mailboxes.

March 12-19: Reading II: Sections 1.3-1.4, Assignment 2

March 19-26: Reading III: Sections 1.5-1.6, Assignment 3

March 26-April 2: Reading IV: Sections 1.7-1.8, 2.1, Assignment 4
(you'll need the program TWODMAPS, downloadable here .)

April 2-9: Reading V: Sections 2.2-2.5, Assignment 5 (omit Glen Q #2)

April 9-12: Reading VI: Section 3.1 and the material on determinants in Section 5.2; scan section 3.2 for related results but do not read carefully. We'll do some practice problems on Friday, but no homework...

April 12-17: Midterm Synthesis Assignment (#6)
Please note the conditions under which this assignment should be written! There is a hand-drawn picture for Q1, obviously missing from the computer file; I've placed a paper copy in your mailboxes.

April 23-May 7: Reading VII: Sections 5.1-5.3, Assignment 7 (This 2-week period incorporates Plan Week)

May 7-14: Reading VIII: Sections 5.6, 6.1-6.2, Assignment 8

May 14-21: Reading IX: Sections 6.3-6.4, Assignment 9

May 21-24: Reading X: Sections 6.5-6.6

May 24-31: Final Synthesis Assignment (#10)

June 4 (?): Final project presentations


Handouts:

Course syllabus

Suggested project topics

Diet preparation example

Diet preparation example (Mathematica)

Row echelon form example

Row echelon form example (Mathematica)


Maple Tips:

Below is a set of Maple commands to allow you to perform many of the operations required for this course. If you have a graphing calculator, you might be able to do most of the tasks required, but I might not be able to help you learn how to use it.


Maple is a command-line environment. You must type a command and hit to generate a response. Don't forget, every command ends with a semicolon.


The LinearAlgebra and linalg Packages

Many of the commands we will need for this course are in a special library of functions called LinearAlgebra, which is not automatically loaded at startup. It is a good practice to load it every time you begin using Maple. Type

with(LinearAlgebra);

(You'll see a list of commands that have been loaded. Eventually you'll grow tired of seeing this list; to suppress it, enter the command with a COLON rather than a semicolon.) A similar package, linalg, may be useful on occasion.


Getting Help on any Command

Maple has extensive help features, not all of which are easy to use. You can browse the help menus; exploring them is the best way to figure out how they work. To get help on a particular command (say, simplify), just enter the following:

?simplify

A rather extensive window describing the simplify command will be loaded.

Don't forget that there is a worksheet containing a general introduction to Maple on my multivariable calculus page.


Use the PALETTES!

Maple has various palettes that make entering various objects, especially vectors and matrices, much easier. Go to the View menu and select the Palettes flyout menu to access them.


Loading Homework Data Files

The CD that came with our textbook contains a variety of Maple worksheets with all the matrices for the textbook homework problems already loaded. More info later on how to use this great time-saving feature...


Performing Row Operations

All row operations can be performed using the RowOperation command. While performing these operations, don't forget that % refers to the results of the previously- executed command. When performing a sequence of row operations, this can be extremely handy!

To switch (say) rows 1 and 2 in matrix A, type

RowOperation(A,[1,2]);

To multiply (say) row 1 by 7, type

RowOperation(A,1,7);

To add to row 2 the result of 7 times row 1, type

RowOperation(A,[2,1],7);


Solving Linear Systems

The LinearAlgebra package contains all the commands you need to solve any kind of linear system.

To perform Gaussian elimination on a matrix A, type

GaussianElimination(A);

To solve the reduced system by back substitution, type

BackwardSubstitute(A);

To reduce the matrix directly to reduced echelon form, type

ReducedRowEchelonForm(A);

To solve the entire linear system, enter into A the matrix containing all but the numbers on the right-hand side of the equal sign. Then enter these numbers as a column vector; let's call it b. Finally, type

LinearSolve(A,b,free='s');

If there are any free variables in the solution, they will appear as s_1,1, s_1,2, etc.


Arithmetic with Matrices

Be warned; this is not as simple as it sounds. You must use the evalm command to do arithmetic with matrices. You can add matrices together, multiply them by a constant, and even raise them to powers just as you might expect:

evalm(4*A);

evalm(A+B);

evalm(A^3);

To multiply matrices together, however, you must use a special way of writing the multiplication sign:

evalm(A &* B);


Transposing a Matrix

The Transpose command is in the LinearAlgebra package, so be sure to load it first. Then type as follows (don't forget the capital T!):

Transpose(A);


Inverting a Matrix

The MatrixInverse command is in the LinearAlgebra package . Then type the following (again, watch lower versus upper case):

MatrixInverse(A);


Performing an LU-Decomposition

This is a little more complicated, because the Maple LU routine actually does a lot more than what we need here. To decompose the matrix A, type

LUDecomposition(A,output=['L','U']);

This will display the L and U matrices, but will not give them names for you to work with later. If you want to give the matrices names (say, Larry and Uma), type

(Larry,Uma):=LUDecomposition(A,output=['L','U']);

You can then confirm the decomposition, if you wish, by multiplying Larry and Uma together:

evalm(Larry &* Uma);



Last modified: April 10, 2002 / Glen Van Brummelen

Office: Dickinson 213. Phone numbers: (w) 440-4467; (h) 440-8142.