Mathematical model. Computer model of a repeated mathematical operation forming a quasicrystal that contains an approximation to a Bessel function. It is generated by repeatedly drawing the same shape. In this case the basic unit is a set of parallel wave lines. These were rotated 21 times around the central pivot point in the yellow region. Similar rules generated the colours shown. The central yellow region is the approximate Bessel function. The rest of the image has regular crystalline properties that deteriorate with distance from the centre: it is quasicrystalline. The slice shows the enlargement of these repeating units. Created as an artwork by Professor Eric Heller.