Random fun with the esoteric bogosort ‘algorithm’ — Surely, there can be nothing worse than permutation sort in terms of performance? Don’t be so sure. And that’s the essence of bogosort: uncertainty. Permutation sort, which I explored previously, has (staggeringly) poor performance, but it does at least offer two guarantees bogosort does not: (1) it is deterministic and…

Software development benefits from a sense of direction — I was changing a lightbulb this morning and was struck by a shift that has occurred in recent years. Lightbulbs used to be sold according to their power consumption. …

Recursion? Iteration? Or a third (or fourth) way? — It has been said that if you want to create something unique, something likely never seen in the universe, shuffle a pack of cards. The probability that the particular arrangement of cards has ever existed before is vanishingly small. The number of permutations of a 52-card deck is 52×51×50×…×2×1, which…

Deconstructing factorial implementations in unnecessary detail, from iterative to recursive, from control structure to data structure, from one language to another — Factorial played a walk-on part in a previous blog post. I’m not saying the reason many programmers are hesitant about recursion is because factorial is their introductory example… but I’m sure it doesn’t help. Now it gets to star in its own mini-series of articles. I want to examine what…

Deconstructing sequential development to better understand more continuous development — Sequential development, as typified by the waterfall model, is the common punching bag of anyone supporting a more adaptive approach to the creation of software. In spite of the increased popularity of iterative and incremental approaches over recent decades — from the classic spiral model to agile development, from RAD…

Practical lessons in the impractical permutation sort — We’ve previously explored esoteric sorting algorithms that either purport to be linear in execution time but are hugely inefficient or actually are linear but are lossy. It’s time to find ourselves at the other end of the scale: lossless and profoundly non-linear. Permutation sort takes us from O(n) to O(n!)…

Figuring out the mass of carbon in the atmosphere with some back-of-the-envelope number crunching — Following on from a previous post, where I looked at how to estimate the mass of Earth’s atmosphere, there’s a question that inevitably suggests itself in this era of climate crisis and the most recent IPCC assessment report: how much carbon is there in the atmosphere? Again this is an…

Dropsort adventures in algorithm design, programming languages and sequential and concurrent control flow — In a previous post I explored sleep sort, a somewhat pathological sorting algorithm that reframes spatial rearrangement as temporal. There is no sense in which the algorithm is intended for practical work, but such esoteric algorithms are useful in what they can teach us about paradigms, performance and programming languages…

Figuring out the mass of Earth’s atmosphere via the back of an envelope — back-of-the-envelope calculation A back-of-the-envelope calculation is an informal mathematical computation, often performed on a scrap of paper, such as an envelope. A back-of-the-envelope calculation uses estimated or rounded numbers to develop a ballpark figure quickly. …