Math 416, Abstract Linear Algebra (Spring 2019)

### Instructor: Pierre Albin

### Office: Illini Hall 237

### Email: palbin [at] illinois .edu

### Lectures:

(B13) MWF 9-9:50 Altgeld 141

(D13) MWF 11-11:50 Altgeld 341

### Office Hours:

Tuesday 15-15:50 and
Wednesday 15:30-16:20

### Web page:
https://faculty.math.illinois.edu/~palbin/Math416.Spring2019/home.html

### Text:
Meckes & Meckes, *Linear Algebra.*

### Assignments:
There will be homework each week due at the beginning of class on
Friday. You are allowed (and encouraged) to work
with other students while trying to understand the homework problems.
However, the homework that you hand in should be your work alone.
Late homework will not be accepted, but the two lowest scores will be dropped.

### Exams:
There will be three midterms (held outside of class) and a final.
We will drop the lowest midterm score.

**First midterm** Feb 11, 19:00-20:30, Engineering Hall 106B1

**Second midterm** Mar 4, 19:00-20:30, Engineering Hall 106B1 (NB drop date March 8)

**Third midterm** April 15, 19:00-20:30, Engineering Hall 106B1

**Final exam** TBA

### Holidays:
Classes begin on January 14 and end on May 1.
There will be no classes on:

**MLK Day**, January 21

**Exam replacement**, February 4 - February 8,

**Spring break**, March 18 - March 22

### Grading percentages:

Problem sets (20%)

Each Midterm (20%)

Final exam (40%)

### Description:

Linear systems of equations show up in all areas of science and
their study has a long history.
A Babylonian clay tablet from around 300 BCE says roughly
There are two fields whose total area is 1800 square yards. One
produces grain at the rate of 2/3 of a bushel per square yard while
the other produces grain at the rate of 1/2 a bushel per square yard.
If the total yield is 1100 bushels, what is the size of each field?

One of the earliest surviving mathematical texts from China, "Jiuzhang
Suanshu" or "Nine Chapters on the Mathematical Art"
(written before 200 BCE) starts
its eighth chapter with the following problem:
A combination of 3 bundles of high-quality grain, 2 bundles of
medium-quality grain, and 1 bundle of low-quality grain will yield
39 barrels of flour. If we combine 2 bundles of high-quality grain,
3 bundle of medium-quality grain, and 1 bundle of low quality grain
we obtain 34 barrels of flour. Finally, combining 1 bundle of
high-quality grain, 2 bundles of medium-quality grain and 3 bundle
of low-quality grain we obtain 26 barrels of flour. How much flour
can be obtained from one bundle of each type of grain?

In modern algebraic notation we might write this as
3h+2m+1l = 39

2h+3m+1l = 34

1h+2m+3l = 26

The method we use today to solve these systems, called Gaussian
elimination in honor of Carl Friedrich Gauss (1777-1855), is the same
method that was used in ancient China!

Eventually it was realized that it is better to think of a system of
equations as a single equation for a vector:

and it turned out that matrices were better understood not just as
coefficients of systems of equations but as maps that transform one
vector into another. This led to considering linear transformations
abstractly and so to the subject known as linear algebra.

Math 416 is a rigorous, abstract treatment of linear algebra.
Topics to be covered include vector spaces, linear transformations,
eigenvalues and eigenvectors, diagonalizability, and inner product
spaces. The course concludes with a brief introduction to the theory
of canonical forms for matrices and linear transformations.