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Sun, 13 Sep 2015 14:04:48 -0700 (PDT) | |
Date: | Sun, 13 Sep 2015 23:04:46 +0200 |
From: | "Nicklas Karlsson (nicklas DOT karlsson17 AT gmail DOT com) [via geda-user AT delorie DOT com]" <geda-user AT delorie DOT com> |
To: | geda-user AT delorie DOT com |
Subject: | Re: [geda-user] Apollon |
Message-Id: | <20150913230446.580ef9269f52c0c73bd62971@gmail.com> |
In-Reply-To: | <B03281A2-123E-4F54-B3AA-CB8CCB09F1B1@noqsi.com> |
References: | <20150913140631 DOT 1da1b78d AT jive DOT levalinux DOT org> |
<201509131529 DOT t8DFTUVS022118 AT envy DOT delorie DOT com> | |
<B0EDB76E-F0DE-4A05-97FC-A405489ACA5A AT noqsi DOT com> | |
<201509131824 DOT t8DIOCBc028428 AT envy DOT delorie DOT com> | |
<B03281A2-123E-4F54-B3AA-CB8CCB09F1B1 AT noqsi DOT com> | |
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On Sun, 13 Sep 2015 13:31:57 -0600 John Doty <jpd AT noqsi DOT com> wrote: > > On Sep 13, 2015, at 12:24 PM, DJ Delorie <dj AT delorie DOT com> wrote: > > > > >> 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. > > > > What I meant to say is that the rational number solution is gridless. It has a base unit, but you can have coordinates like 45634/1299709. It actually sound good if it could be implemented with a reasonable effort in practice.
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