A few months ago, I bought a copy of *Math Doesn’t Suck* by Danica McKellar at a BOOKSALE outlet. (Click on the images to see higher-resolution versions.) I know she has experience being a mathematician, but I didn’t know how much experience she has being a mathematics educator. I had done some study on conceptual and procedural knowledge in mathematics so I was very curious to know which she would introduce first—concepts or procedures—and which she would emphasize more. Read the rest of this entry »

In a tribute to the mathematician Israel Moiseevich Gelfand (*Notices of the AMS*, vol. 60, no. 2, p. 162), Dusa McDuff recalls meeting Gelfand in Moscow.

Then [Gelfand] gave me his recent paper on Gelfand-Fuchs cohomology to read. It was titled “The cohomology of the Lie algebra of vector fields on a manifold”, but I had been so narrowly educated that I didn’t know what cohomology was, what a Lie algebra was, what a vector field was, or what a manifold was.

I know one definition of a vector field, but it’s probably not the same as the one in the paper mentioned. Right now I also don’t know the definitions of the other three terms.

I recently bought a copy of Martin Gardner’s *The Universe in a Handkerchief* (New York: Copernicus, 1996). (In a future blog post, I’ll describe in more detail how I bought it.) The book’s subtitle is “Lewis Carroll’s Mathematical Recreations, Games, Puzzles, and Word Plays.” I present here some items in the book that I found very interesting. Read the rest of this entry »

In an earlier blog post, I showed the solution to a first-order linear system of two (ordinary) differential equations with constant coefficients for the case where the characteristic equation of the (constant coefficient) square matrix has repeated roots. In particular, I considered the system , where are real constants and are real variables, for the case where and . Now I look at the case where . Read the rest of this entry »

Here’s a funny comment on this answer at Mathematics Stack Exchange.

On being presented an equation where the left-hand side’s terms have a factor of 1/2 and the right-hand side is constant, a user asks “why not multiply through by 2?” Another user replies “Because this is physics.”

I was looking through the Rare Books section of the AbeBooks website a few days ago and searched for some books with the keyword *math*. The first entry is shown above, a book by Copernicus published in 1542. (It seems that the books with the highest prices are listed first.) A quick internet search reveals that the $350,000 price for this book is reasonable. (But I doubt that anyone interested in buying the book would have it shipped for $6.50.)

The second book on the list is shown above, a book published in 1990. There are three copies of this book for sale. Which one would you choose, the one priced at $149.90 or the one priced at $118,935.97?

From Sir Arthur Conan Doyle’s “Silver Blaze”:

Gregory (Scotland Yard detective): “Is there any other point to which you would wish to draw my attention?”

Holmes: “To the curious incident of the dog in the night-time.”

Gregory: “The dog did nothing in the night-time.”

Holmes: “That was the curious incident.”

My daughter found a copy of Mark Haddon’s The Curious Incident of the Dog in the Night-Time (Vintage, 2004) at a local BOOKSALE outlet and I bought it because she liked it. I very seldom look at novels, but I’m glad that I read this book.

This “murder mystery novel” is quite unusual in that (a) it starts at chapter 2, (b) it has footnotes, drawings, and an appendix consisting of a proof of a mathematical theorem, and (c) the murderer is revealed halfway through the novel.

So I think it is not a “real” murder mystery novel (hence the scare quotes in the previous paragraph), and, to paraphrase Sherlock Holmes, that is the curious incident.

Although the story is told from the viewpoint of a 15-year-old boy, I found the observations on language (literal and figurative), writing (how to write detective fiction), the nature of the mind (how a normal person’s way of thinking differs from that of an autistic person, or of an animal, or of a computer), and mathematics very deep. I particularly like how a wide variety of mathematics is presented (probability, chaos, games, tessellations).

A quote from Wikipedia mentions that the book “was published simultaneously in separate editions for adults and children.” It seems that my copy has a few differences from the version that Wikipedia refers to. For example, Wikipedia mentions that the lead character is given a Cocker Spaniel puppy at the end, but in my copy of the book, the puppy is a Golden Retriever.

I found the ending quite sad, although most people would probably consider it a happy ending.

The 2014 Bicol Mathematics Conference will be held on February 7–8, 2014 at the Ateneo de Naga University. We are inviting mathematicians and mathematics educators especially those in the Bicol region to present a 30-minute talk. More details can be found in the call for papers.

I’m currently teaching an undergraduate course on ordinary differential equations using the 8th edition of *Elementary Differential Equations* by Rainville, Bedient, and Bedient (published in 1996 by Prentice Hall). I’ve always wanted to have a blog post containing some LaTeX (using the plug-in WP LaTeX), so in this blog post I’ll be showing my solution to one of the exercises in the book.

I will derive the solution to a first-order linear system of two (ordinary) differential equations with constant coefficients for the case where the characteristic equation of the (constant coefficient) square matrix has repeated roots.

Read the rest of this entry »