Question about creating a primitive

[Manfred Schaefer]

I think the "inaccuracies" are from the process/definition of the prims...
a ring18 connects a cyl scaled x18 with one scaled x19, which means the rounding imperfections from the cyl prims get amplified.
(I dont know exactly but it fits: edge/cyl prims have 0.9239 0 0.3827 for the 22.5° position, this multiplied with 19 results in your 17.5541 0 7.2713 values)

Hello,

Thanks for your reply. Philippe's explanation has helped me understand why rounding errors are accepted and why this approach makes sense.
The primitives are defined as size one and can be scaled by any factor; the error that results from this is the same for all primitives. This is different from when rounding is only performed at the end.