### Review: The Mathematics of Secrets by Joshua Holden

Any book on cryptography written for a more-or-less lay audience must inevitably face comparisons to The Code Book, written in 1999 by Simon Singh, the king of distilling complex subjects to a few hundred pages of understandable writing. While Singh’s book is a pretty thorough history of codes and codebreaking through the centuries with plenty of the maths thrown in, The Mathematics of Secrets is tilted (and indeed titled) more towards a fuller explanation of the mathematical techniques underlying the various ciphers. Although Holden’s book follows a basically chronological path, you won’t find too much interest in pre-computer ciphers here: Enigma is cracked on page seventy, and the name Alan Turing does not appear in the book.

### Review: Hidden Figures

Mega-late to the party, I’ve now arrived back from a week lecturing in Indonesia and have found time to go and see the incredibly well-received and widely talked-about NASA women maths film, Hidden Figures. I’ve heard an incredible number of wildly positive responses to the film, from as long ago as January, and have been looking forward to it greatly.

The film is a painstaking and at times brutally realistic depiction of the struggles faced by African-Americans, and by women, during the era of the early space missions.

### Relatively Prime Recap: Season 2, Episode 8: Diegetic Plots, Chapter 2

There really isn’t enough silliness in maths. Samuel has tried to inject some throughout the series, sometimes more successfully than others. This is the episode where he finally nails the silliness.

Diegetic Plots, Chapter 2 is a nice finale to a generally good season of Relatively Prime. Dealing with sketches and haiku from the mathematical domain, we get a glimpse of the daft side of maths.

### Relatively Prime Recap: Season 2, Episode 7: $f(\theta) = 1 – \theta$

I’d have written it as $r = 1 – \theta$, myself, but even then it’s not much of a heart. However, that’s pretty much my biggest gripe about this episode, the penultimate in series 2 of Samuel Hansen’s one-of-a-kind mathematics podcast, Relatively Prime.

Episode 7 is subtitled “Dating in the mathematical domain”, and looks at the maths involved in dating and relationships, and begins with some of the comments Sam’s dating profile received from non-mathematicians. Now, denizens of the dating world: Samuel has many flaws and failings; picking on the fact that he’s a mathematician seems a little arbitrary and unfair, like deciding not to vote for Donald Trump because you don’t like his tie. I have this unfamiliar sensation. Could it be… surely not? It appears that I feel a little sorry for Samuel. Don’t tell him, ok?

### Relatively Prime Recap: Season 2, Episode 6: Principia Metropolica

I’ve been looking forward to this one: cities in the mathematical domain. This is the kind of applied maths I can really get behind.

Samuel starts with Mike Batty of University College, London’s Centre for Advanced Spatial Analysis discussing how cities grow and organise themselves. The structure is frequently fractal; how does one calculate the dimension of a city?

From a top-level view of cities, he moves on to a low-level description of one of the biggest problem in cities: traffic (another thing that fascinates me). We get a glimpse of traffic waves, and the unfairness that the person responsible for the average jam doesn’t suffer from the effects. And we learn that Gábor Orosz (University of Michigan) tests his hypotheses using robots as well as simulations.

### Relatively Prime Recap: Season 2, Episode 5: Other Duties As Assigned

For about 40 minutes of this week’s episode of Relatively Prime (Number 5 of 8, already? Good heavens!), Samuel Hansen looks like he’s managed to escape from his shameful, borderline criminal, past in Las Vegas. But he’s pulled back in for one last job, which is a debacle, of course.

### Relatively Prime Recap: Season 2, Episode 4: Diegetic Plots, Chapter 1

On top of the usual disclosures, I should add that Dave Gale and I interviewed Samuel Hansen this week for our Wrong, But Useful podcast, which you might like to listen to for a deeper insight into Samuel’s brain.

During the conversation, he warned me I wouldn’t like Episode 4 of the new Relatively Prime, “Diegetic Plots, Chapter 1”. I don’t know if that was expectation management or an elaborate double bluff, but the joke’s on you, Hansen: I jolly well did like it, so there!