This Demonstration shows approximations of the boundary (clockwise) of some discrete families of iterated functional systems (IFS),

, which can be thought of as the fractional part of numeration systems with a complex base,

.
Change

and

to choose one of the periodic cases. The next slider "shown recurrence level" lets you choose the level of approximation and the rotation of the recurrence relation; for example, '

' represents the

iteration. These relations show that an edge with given previous direction (red) changes into the resulting sequence of edges. Ignoring order gives the matrix with dominant eigenvalue (

) and corresponding eigenvector, which gives the limit distribution of the number of edges. In the limit the figure becomes a fractal with the Hausdorff dimension

.