Category Archives: Linear Algebra

What’s an eigenface?

With the recent korean wave, we get to see lots of Korean pop, tv, movie stars in the media. But I found that I can never tell them apart. Especially, the ladies, tall, thin, beautiful but too homogenous. (Of course, … Continue reading

Posted in Applications, Fun Stuff, Linear Algebra | Leave a comment

A $23 million dollar book

A very interesting post. http://www.michaeleisen.org/blog/?p=358 It is not merely the astronomical price tag but the clever detective work that figured out what lead to the crazy price and is a good example of how algorithms can go wrong. Finally it … Continue reading

Posted in Books, Fun Stuff, General, Linear Algebra | Leave a comment

Statistics and student behaviour 2

continuation of a previous post. Last year, for the very first time I had my full lecture series made available as webcasts. I’ve always not been a fan of doing this and managed to avoid it so far because I … Continue reading

Posted in Linear Algebra, Statistics, Teaching, Technology | Leave a comment

Simple algebra*

In the midst of grading exams now. One problem consists of computing determinants and many students give the answer [tex] (1+a)^3 -3a -1 [/tex] without simplifying it to [tex] a^3+3a^2 [/tex]. I have this nagging suspicion that they are not … Continue reading

Posted in Algebra, Linear Algebra, Teaching | Leave a comment

Statistics and student behaviour 1

I have a couple of statistics that I compiled this year for my 400 student course on linear algebra. Submitting in class worksheets. I set 10 worksheets over the the semester and distributed them to students during lectures to be … Continue reading

Posted in Linear Algebra, Statistics, Teaching | 1 Comment

Purse of Denari

A problem from MAA website dating back to Fibonacci. Four men already having denari found a purse of denari; the first man said that if he would have the denari from the purse, then he would have twice as many … Continue reading

Posted in Linear Algebra | 1 Comment

Charles Dodgson

Picked up a copy of Lewis Carroll in Numberland by Robin Wilson from the library. I must admit that I browsed through it instead of reading it, picking up bits and pieces that I find interesting. For example, it is … Continue reading

Posted in Books, Fun Stuff, Linear Algebra, Quotes/People | 1 Comment

Euler’s Rotation theorem in 3D

Any rigid body displacement where a point is fixed is equivalent to a rotation. I saw this neat proof from Don Koks’ Explorations in Mathematical Physics. By the hypothesis [tex] |Ar| = |r| \implies r^t A^t A r = r^t … Continue reading

Posted in Books, Geometry/Topology, Linear Algebra | 1 Comment

One Matrix, Inverted

Another gem from The Lady Tasting Tea. The mathematical theory of input-output analysis requires that the matrix that describes the economy have a unique inverse … Leontief’s initial set of sectors led to a 12 x 12 matrix, and Jerry … Continue reading

Posted in Fun Stuff, Linear Algebra | 1 Comment

Monkey Tricks

If you go to the zoo, the chimpanzee will wave to you. I do not understand their psyche, but I presume they do not understand what they are doing, except when they wave, they get food. I still remember seeing … Continue reading

Posted in Linear Algebra, Teaching | 1 Comment

Misnomers

I just read (from a text by K Hardy) that the Vandermonde determinant was named after Vandermonde by Henri Lebesgue, and was not ever recorded in Vandermonde’s work. The list of other Misnomers Pell’s equation: Nothing to do with Pell, … Continue reading

Posted in General, Linear Algebra | 5 Comments

New Edition

I will be teaching Linear Algebra next semester and so I now have two copies of the same textbook with me. When I learnt the subject, we used the 7th edition, this time round, I will be teaching from the … Continue reading

Posted in Books, Linear Algebra | 3 Comments