Category Archives: Linear Algebra


It’s slightly old but I only recently saw this article about how Google Translate make use of linear transformation. The new book on my desk eta products and theta series identities has the following quote in the preface. In der … Continue reading

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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

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A $23 million dollar book

A very interesting post. 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

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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

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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

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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


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