Hi Mike, 
 
It is not very important.  Just came up when I wanted an actual half nephroid. 
I was just observing that zooming way in to a cusp point shows a hairpin turn, rather than a corner point, a result of interpcurve. 
Identifying the cusp points, and ending the interpcurve there, would result in a "corner." 
 
For example, for 3 cusps in an angle of 2 PI, the ratio of a/b = 3.  Numcycles = 1/3 becomes 2PI/3 inside the js code, and yields one lobe. 
Numcycles could be changed from an integerValue to numericValue. 
Circular array, or 3 interpcurves would yield the full curve...  
 
 
A ranunculoid has 5 cusps. 
 
- Brian 
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