MATH 340
Elementary Matrix and Linear Algebra
University of Wisconsin - Madison
University of Wisconsin - Madison
MATH 340 is a basic linear algebra course which focuses on vectors as ordered sets of real numbers and linear operators as matrices. In this course the focus is typically on computational aspects of the subject with some lighter treatment of the more theoretical points.
Students who complete this course and would also like exposure to differential equations should consider MATH 319.
In summary, MATH 340...
Is ideal for students who need functional knowledge of basic matrix algebra, and in particular those looking for applications featuring discrete mathematics (i.e., computer science and possibly statistics);
Is not by itself sufficient for enrollment in advanced math courses.
There were homework assignments, but they weren't graded. In addition, we had supplementary exercises, which consisted of problems from the textbook.
The textbook problems were detrimental in helping me better understand the material and do well on the exams. I found this course to be a little easier than some of the other math courses I have taken at UW-Madison. Some of the topics are a bit tricky to grasp, but after doing 4-5 problems, they also become familiar. The lecture notes were more useful for understanding the concepts and how to start a problem, and the discussion worksheets contain questions very similar to the exam questions.
I highly recommend Professor Harry Lee. He taught this class while it was online, but the (asynchronous) lectures included both proofs and easy-to-comprehend examples. Any questions we asked were always taken seriously and explained in multiple ways. It was clear that he truly cared about how we fared as a class.
Overall, I would say that Professor Lee's exams were fair. Although there were 1-2 questions that asked for you to show something is true, a lot of these "proof-based" questions were either outlined in lectures, discussion worksheets, or in the textbook. Other than the proof-based questions, the other questions were computation-based. For example, they asked us to compute the determinant of a 3x3 matrix, to find span of a set of vectors, etc.
I used the textbook questions, especially the supplemental questions, to study for the exam. A lot of the questions in the book are similar to the type of questions asked in the exam. Professor Lee also recommended looking over his posted lecture notes and re-doing the discussion worksheets.
I was extremely lucky because I was able to host a review session on Zoom for each of the exams, and one of the TAs hosted review sessions for the first two exams. The review sessions were super helpful for helping me find gaps in my knowledge. Below are the recordings from the review sessions I lead, one for each exam. There is a section with notes and some of my thoughts about each of the sections of the course. Each set of recordings include a PDF of the problems I went over.
EXAM 1 REVIEW MATERIAL
Topics:
Linear Systems
Matrix Operations
Properties of Matrix Operations
Symmetric Matrices
Skew Matrices
Nonsingular Matrices
Partitioned Matrices
Matrix Transformations
REF and RREF
Inverse of a Matrix
Determinant of a Matrix
Properties of Determinants
Cofactor Expansion
Notes:
Most of these topics are tools for topics later. It was highly recommended to do many practice problems and become good at row reductions, calculating determinants, and finding the REF & RREF form of a matrix. Additionally, there are many equivalent statements to reference for nxn matrices. From my experience, I highly recommend creating a list of these statements and adding onto them as the course progresses. The list made it a lot easier to see the connections between the topics.
Here is a list of the most important things/concepts in this first 1/3 of the semester:
Finding solutions to a linear system
Has no solution
Has a single/trivial solution
Has infinite solutions
Definition of a nonsingular matrix
Finding row reduced form (REF)
Finding row reduced echelon form (RREF)
Using the inversion method to find the inverse of a 2x2, 3x3, and 4x4 matrix
Finding the determinant of a 2x2, 3x3, and 4x4 matrix using cofactor expansion
EXAM 2 REVIEW MATERIAL
Topics:
Inverses Using Cofactors
Cramer's Rule
Vector Spaces
Subspaces of Vector Spaces
Span of a Subspace
Linear Independence
Basis of a Vector Space
Dimension of a Vector Space
Null Space of a Vector Space (titled Homogeneous Systems)
Nullity of a Vector Space (titled Homogeneous Systems)
Rank
Transitions Between Basis (titled Coordinates)
Magnitudes of Vectors
Dot Product
Cross Product
Inner Products
Notes:
After finishing this course, I discovered that there are 7 different concepts that were crucial in this section and in later sections. Side note, as the topics got more complicated, it really helped me to be able to remember the properties linearly independent vectors had. Not only did the problem become much simpler, but there are other equivalent statements that I could use.
Here is a list of the most important things/concepts in the 2nd 1/3 of the semester:
Span
Linear independence
Null space/nullity
Basis
Column Rank
Transition matrices between two different basis (neither of which is the canon basis)
Dot product/inner product for vectors
Part 1: Chapter 3.4, 3.5, 4.2, and 4.3 (quick overview)
Part 2: Chapter 4.6
Part 3: Chapter 4.7
Part 4: Chapter 4.8, 4.9
EXAM 3 REVIEW MATERIAL
Topics:
Gram-Schmidt process
Orthogonal complements
Projection of vectors onto subspaces
Linear transformations
Standard matrix representation of linear transformations
Matrix representation of linear transformations with respect to 2 basis
Kernel of a linear transformation
Range of a linear transformation
Eigenvalues, eigenvectors, and eigenspaces
Diagonalization
Orthogonal diagonalization
Notes:
From all of the problems I had done on these topics, I realized that the last section relied heavily on prior sections. I had to frequently do/use the following concepts:
find the null space of A
find the column space of A
know the definition of being orthogonal and of being a normal vector
use the inversion method on 2x2, 3x3, and 4x4 matrices
find transition matrices between two basis
calculate the determinant of 2x2, 3x3, and 4x4 matrices
Especially for the last 3 chapters, being able to find the determinant of 3x3 and 4x4 matrices quickly is a must! These last chapters were the hardest, in terms of grasping the concept. However, after a bunch of practice problems, they become much, much, MUCH easier.
Part 1: Chapter 5.5, Chapter 5.6, and comments on the Gram-Schmidt process and on orthogonal complements
Part 2: Overview of Chapter 6.1, Chapter 6.2, Chapter 6.3, and comments on the finding the matrix representation using the inversion method