The day my unit tests validated a thousand wrong calculations — I was so embarrassed. I thought I had done everything right. I wrote some code that performed some complicated floating point calculations. Like a good developer should, I wrote unit tests that compared the results with expected values. Everything was working great. Or so I thought. A few days later…

Design and program your own data capture hardware — Recently I was thinking about the nonlinear behavior of diodes. In college, I learned that the current through a diode is approximated by an exponential function of the voltage applied to it. I wondered how well exponential functions describe the current/voltage behavior of a real-life diode. I thought it would…

Situations where labeled branching makes your C code better — In 1968, Edgar Dijkstra wrote the influential essay Go To Statement Considered Harmful. He argued that the use of unconditional branches, commonly known as goto statements, should be abolished from high level programming languages. The animosity against goto statements is well-deserved. Everyone who has programmed in BASIC or older dialects…

The right way to represent a finite set of alternatives — Often, programmers wish to represent something in their code whose value must belong to a predetermined, finite collection of values. Examples include: Days of the week: Monday, Tuesday, …, Sunday. Types of image file format: JPEG, PNG, GIF, …. The suits in a card game: club, diamond, heart, spade. The…

How it’s possible to beat world-class compression algorithms in certain special cases — There are several powerful data compression programs in widespread use. Some famous examples are gzip, bzip2, and pkzip. Recently I started wondering if, given a specific input file to be compressed, I could create an algorithm that outperforms all of these programs. The Challenge I decided to make it a game for…

A language feature that unpleasantly surprises almost everyone — Many programming languages allow you to write functions that accept optional arguments. Python is one of them. This is a handy way to make function calls concise (when an argument can be omitted) and flexible (when a particular argument value is needed). But there are dangers lurking for the unwary. An Example …

Curiosities, triumphs, and horrors from a Victorian era textbook — One afternoon while on vacation, I decided to wander into a used book store. Along with the usual cookbooks and paperback romances, I located a rare treasure. It was an 1879 science and technology textbook called A Natural Philosophy by G. P. Quackenbos, LL.D. …

Some friendly advice from the CDC — if you know what’s good for you — As the director of the CDC’s Department of Epidemic Nomenclature, I have taken some heat recently. The Corona beer people are livid that I selected the now-infamous name coronavirus disease 2019 (COVID-19). …

With a C++ demo to create a fractal zoom — If you are a computer programmer who has ever thought of creating a video that contains a computer-generated animation, this article is for you. Here I will assume that you have existing code, or can write code, that creates some kind of image as a two-dimensional array of pixels. …