DRAKULA stands for Dragon Curves Superimposed (German: Drachenkurven überlagert). The dragon curve is a fractal object. The basic idea was first explored by NASA physicists John Heighway, Bruce Banks, and William Harter and described by Martin Gardner in his 1967 Mathematical Games column in Scientific American. However, the mathematical theory for this was not developed until 1970 by the mathematician Chandler Davis and the computer scientist Donald Knuth.
Dragon curves are created by sequences of left and right turns according to certain rules. The program allows dragon curves of different orders – or sections of them – to be lined up and superimposed. Left and right turns were not only represented in the usual way by right-angled bends but also by mathematically defined elements, such as triangles or curved sections of curves with multiple curves. These elements were designed in such a way that when they are superimposed, clearly recognizable new form elements are created through overlaps and attachments. The superimposition of closed curves in different colors is particularly attractive. The dragon curves were also interesting for Franke as an object of experimental aesthetics and for his studies on information psychology, since here the rare case of an easy possibility of specifying their statistical information (complexity) occurs; this is equal to the number of 0,1 indications used to construct it.
Franke also overlaid dragon curves – mostly mirrored – and not only used straight lines as individual elements but also other shapes, such as semicircles or triangles, as basic elements.
The pictures of DRAKULA were made with a Siemens System 4004. The Fortran program was written by Peter Henne from the Gesellschaft für Datenverarbeitung GMD according to detailed specifications from Franke. The plots were realized by Peter Vordermaier at Siemens AG. A complete printout of the program is available.