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circles exist with NURBs, iirc. Now at some point you have to turn on individual pixels, so ....

but until then, figuring out micron level tolerances over meters can be done with perfect circles using Non Uniform Rational B(Basis)-Splines.

Not if you use a vector display!

I could be completely incorrect here; but I don't know of a vector display that can do anything but arbitrary lines. Circles are usually rendered with sublinears to the command resolution (and trace runs) you're willing to sacrifice.

An oscillating display can do curves, but only in a wave/ linear sequential fashion.

You're probably right, but I don't think there's any fundamental obstacle to controlling a CRT electron beam to trace arbitrary curves – there's vertical control and horizontal control and you can arbitrarily modulate them over time, can't you?

I didn't say it wasn't theoretically possible, I said there are no (that I know of) concrete implementations of this idea.

Yes, this is theoretically possible. I imagine it wasn't done due to processing limitations during the time vector displays were common; but my limited knowledge in the realm doesn't give me certainty.

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