Both Quito in Ecuador and Singapore are on the Equator. One can fly due eastward from Singapore and reach Quito in due course. However, this is not the shortest route. The equatorial trans-Pacific route from Singapore to Quito is not a geodesic on Earth! Why not?

## Archive for the 'Occasional' Category

### Fourier’s Wonderful Idea – I

Published March 29, 2018 Occasional Leave a CommentTags: Analysis, History

**Breaking Complex Objects into Simple Pieces**

“In a memorable session of the French Academy on the

21st of December 1807, the mathematician and engineer

Joseph Fourier announced a thesis which inaugurated a

new chapter in the history of mathematics. The claim of

Fourier appeared to the older members of the Academy,

including the great analyst Lagrange, entirely incredible.”

** Introduction **

The above words open the *Discourse on Fourier Series*, written by Cornelius Lanczos. What greatly surprised and shocked Lagrange and the other academicians was the claim of Fourier that an arbitrary function, defined by an arbitrarily capricious graph, can always be resolved into a sum of pure sine and cosine functions. There was good reason to question Fourier’s theorem. Since sine functions are continuous and infinitely differentiable, it was assumed that any superposition of such functions would have the same properties. How could this assumption be reconciled with Fourier’s claim?

“It is difficult to imagine modern mathematics without the concept of a Lie group.” (Ioan James, 2002).

Sophus Lie grew up in the town of Moss, south of Oslo. He was a powerful man, tall and strong with a booming voice and imposing presence. He was an accomplished sportsman, most notably in gymnastics. It was no hardship for Lie to walk the 60 km from Oslo to Moss at the weekend to visit his parents. At school, Lie was a good all-rounder, though his mathematics teacher, Ludvig Sylow, a pioneer of group theory, did not suspect his great potential or anticipate his remarkable achievements in that field.

### Subtract 0 and divide by 1

Published March 8, 2018 Occasional Leave a CommentTags: Analysis, History

We all know that division by zero is a prohibited operation, and that ratios that reduce to “zero divided by zero” are indeterminate. We probably also recall proving in elementary calculus class that

This is an essential step in deriving an expression for the derivative of .

### The Evolute: Envelope of Normals

Published February 22, 2018 Occasional Leave a CommentTags: Analysis, Geometry

Every curve in the plane has several other curves associated with it. One of the most interesting and important of these is the evolute.

Godfrey Harold Hardy’s memoir, *A Mathematician’s Apology*, was published when he was 63 years old. It is a slight volume at just 90 pages, but is replete with interesting observations and not a few controversial opinions. After 78 years, it is still in print and is available in virtually every mathematics library. Though many of Hardy’s opinions are difficult to support and some of his predictions have turned out to be utterly wrong, the book is still well worth reading.

### Kaprekar’s Number 6174

Published January 25, 2018 Occasional Leave a CommentTags: Number Theory, Recreational Maths

The Indian mathematician D. R. Kaprekar spent many happy hours during his youth solving mathematical puzzles. He graduated from Fergusson College in Pune in 1929 and became a mathematical teacher at a school in Devlali, north-east of Mumbai.