What is it ? :
This formula is a kind of "generalisation" of Mark Townsend's great Vine formula. Note that you must use an outside coloring other than "None" in order to see something. The best coloring for this kind of formula is IMO Mark's "Magnitude" (in mt.ucl), but other ones (especially fbm) can give nice results.
The Parameters :
Alpha : Same parameter as in Vine. The bigger it is, the smaller the pattern become.
Flavour : (only integers) Determines the number of "inner" loops the formula performs. The bigger it is, the more complex (or messy) the pattern become.
Start : This is something new. The vine formula is essentially made of sinus with real arguments. When the "start" value is not (0,0), an imaginary part comes in the sinus. The effect is that the pattern becomes a bit dislocated and the spirals tend to disappear. Don't use too big numbers for this parameter...
Step size (I and II) : Determines how sharp the pattern will be. The "imaginary" part of this parameter will be used in a cosinus instead of a sinus, so varying the ratio real part/imaginary part will change the shapes.
Try also changing the number of iterations. Increasing it will increase the complexity and the sharpness of the pattern.