# Blog

## A Fix for Pysolfc on Linux Mint 21 Vanessa

There are problems playing the pysolfc solitaire game on the latest release of Linux Mint 21 (Vanessa).

The game requires the formatter module from the Python Standard Library, which had been deprecated since Python 3.4, and has been removed in Python 3.10.

An easy, but ad-hoc workaround goes as follows:

## Running a GUI Application in a Docker Container

Containers are not usually associated with GUI applications, but there may be times when one might still want to run such a program inside a container, for example to isolate the application’s dependencies. Installing a GUI application in a container means that not only the application, but also all its specific dependencies are encapsulated inside the container (respectively, the container image), and can therefore reliably be removed from the system in a single step.

## Using Xsession to Set an Environment Variable Without a Shell

The freedesktop project, arguably the most important Linux organization you’ve never heard of, has (among many other noble deeds) done an admirable job clearing up the mess of local cache and config files in one’s home directory. But how does one override their defaults, if this requires setting environment variables globally, for all processes, and outside an explicit shell environment?

## A Look at the HDF5 Format

I occasionally see references to the HDF5 file format, but I have never encountered it in the wild. But a recent project generated multiple data sets simultaneously, in addition to metadata. Was there a better way than maintaining a collection of flat files? This prompted me to look at HDF5.

## The Heilmeier Catechism

George H. Heilmeier, director of DARPA (the advanced-technology research agency of the US Defense Department) from 1975 to 1977, formulated a set of questions to help evaluate research proposals.

## A Strictly Geometrical Proof of the Altitude Theorem

The Altitude Theorem or Geometric Mean Theorem is a result from high-school geometry. In a right triangle, the altitude $h$ on the hypotenuse divides the hypotenuse into two segments, $p$ and $q$. The theorem now states that $h^2 = pq$ or, equivalently, $h = \sqrt{pq}$: the altitude equals the geometric mean of the segments of the hypotenuse.

The content of this theorem is a bit surprising, because the altitude and the hypotenuse segments seem geometrically somewhat “unrelated”: it’s not clear how one could (geometrically) be transformed into the other. And although the theorem can be proven in many different ways, many of the proofs are at least partially algebraic, and therefore do not provide an intuitive, geometric sense why it is true. But it turns out that a very elegant, strictly geometric proof of this proposition can be constructed.

## Two Further Hugo Gotchas

I just wasted one hour and five minutes, dealing with two of these opaque, unexpected, and almost undiagnosable showstopper roadblocks that Hugo will throw your way - much too often, in my opinion.

## The Diamond-Square Algorithm for Terrain Generation

The Diamond-Square Algorithm is the natural first stop for generating artificial landscapes. The algorithm itself is beautifully simple (more details below, and on its Wikipedia page). But a casual implementation ended up not working at all, prompting me to look for an existing implementation to learn from. However, most implementations I found looked hideously complicated (or just hideous), not necessarily correct, and/or used out-of-date programming languages and styles. It therefore seemed like a good idea to create a clean, simple “reference” implementation of this algorithm, using a contemporary and widely known programming language and style.

## Solving a 1993 Programming Challenge in 2022 (Updated)

I recently came across a collection of old (1990s) “programming challenges”. I thought it might be amusing to tackle one of these challenges using technologies from the period in which they were posed, and compare the solution to one using contemporary techniques. In other words, do the same problem in C and Python.

## On Web Design

When doing research to get this website up and running, I came across the following two truly inspiring examples: