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Date: Sun, 13 Sep 2015 14:24:12 -0400
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From: DJ Delorie <dj AT delorie DOT com>
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	John Doty on Sun, 13 Sep 2015 10:18:56 -0600)
Subject: Re: [geda-user] Apollon
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> If you do this right, you wind up with *exact* knowledge of every
> point in the x/y Cartesian geometry. Sines and cosines of these
> angles are rational numbers. No roundoff error. You can choose any
> unit basis you want (I'd go with meters).

I thought of this for arcs - define the endpoints and the radius, not
the center and angles (there are other issues in this example, but
still).  You're limited to what snaps to your grid, but if your grid
is nanometers that's a very small error.

You do tend to go off-angle pretty quickly though, since so many
angles result in irrational numbers.