One of the things that interests me is the way in which diagrams and charts, stripped of their original context, can be considered works of art in their own right. Most such charts being generated by software these days, it is a short step to writing software specifically for the purpose of generating chart-like art without any informational content.
As with all algorithmic art, this raises interesting questions about which level of abstraction contains the work of art. Is it the program itself, one of its potential outputs, or the entire set of its possible outputs?
Abstract Grid Generator
The default display in this case is a reasonably faithful imitation of a piece of pseudo-"digital" background illustration from a 1980s textbook. The original piece appears to have been implemented in gouache or acrylics, and there is noticeable variation in the middle shade of blue used by the small squares. This has been emulated here by using two similar colors, which -- to me, at least -- creates a subtle, continuous variation that helps keep the resulting image from having the flat and boring look that many continuous-tone digital illustrations possess.
Harmonic Progression Calculator
Quoth Wikipedia: "In mathematics, a harmonic progression (or harmonic sequence) is a progression formed by taking the reciprocals of an arithmetic progression. In other words, it is a sequence of the form
where −1/d is not a natural number and k is a natural number." The following tool lets you set values for a, d, and the size of the progression, k, and it then generates both the numeric values and a simple graphical representation. (The graphical version uses the absolute value of the sequence elements to avoid the problem of dealing with negative lengths.) Enjoy!