Wallpaper: Split Time

(Split Time, 1920×1200)

You can find more backgrounds here.

Analog Thinking

About five years ago, I found an old book, probably now an introuvable, Korn and Korn’s Electronic Analog Computers (D-c Analog Computers), 1956 [1].

Well, that mostly unrelated to today’s post, except that in some cases, relatively crude analog methods may give surprisingly good results in numerical problems (the topic came up while I was discussing the golden ratio and its place in art with friends, trying to make a point that it was mostly heuristic, bordering on the numerological). Take the pyramids, for example. The Ancient Egyptians did not have GPSes and laser guided telemetry. Yet, they managed to get some of their buildings incredibly well aligned with the celestial north.

Programming Challenge: Martian Calendar

This week, another programming challenge, but this time considerably tougher than the previous.

His Imperial Majesty, Xórgü of House Nand, decrees that the martian imperial court is in need of a new calendar. The current martian calendar counts 668 days, but it accumulates errors. The martian year, according to His Imperial Majesty’s most illustrious astronomers, is in fact 668.60 (martian) days long.

Lost+Found: Harder, Better, Faster, Stronger… typography?

Programming Challenge: Luminance

A few years ago, I posted on my personal web page a number of programming challenges for my friends. This week, I present one of the old challenges: computing luma from RGB triplets using integer arithmetic only.

Compiling Python

As I take a new (professional) interest in Python, I use it more often. I noticed on previous occasion that the default interpreter’s performance is dismal, and I concluded that the next logical step would be to recompile it to get better performance.

It would not prove easy.

Suggested Reading: The Information

James Gleick — The Information: A History, A Theory, A Flood — Pantheon Books, 2011, 544 pp. ISBN 978-0375423727

(Buy at Amazon.com)

This book is written for a non-technical audience. It introduces the reader to information theory, from Ancient Times to quantum computers. There is very little math—well, there are two or three formulas—but the text focuses on giving the reader the essential gist of information theory, that is, the nature of information itself and how information necessarily uses energy to be processed or to even exist.

It’s not a book that will change your life forever, but is still worth the read. A good summer book.

Surrogate Functions

In some optimizations problems, the objective-function is just too complicated to evaluate directly at every iteration, and in this case, we use surrogate functions, functions that mimic most of the properties of the true objective-function, but that is much simpler analytically and/or computationally.

Lately, I have done some thinking about what properties a surrogate function (or surrogate model) should have to be practical.

Wallpaper: 5:59

(5:59, 1920×1200)

Building a Personal Library (Part II)

Quite a while ago, I blogged about how to find used books to fill your personal library on a budget. But used books have a major drawback compared to new books: they’re used. Well, yes, of course, but that means they may be in less than perfect state. They can be scratched, missing a few pages, have a damaged cover.

Fortunately, minor defects are rather easy to fix with a little creativity and surprisingly little material.