X-Authentication-Warning: delorie.com: mail set sender to geda-user-bounces using -f
X-Recipient: geda-user AT delorie DOT com
X-TCPREMOTEIP: 207.224.51.38
X-Authenticated-UID: jpd AT noqsi DOT com
Content-Type: text/plain; charset=us-ascii
Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\))
Subject: Re: [geda-user] Apollon
From: John Doty <jpd AT noqsi DOT com>
In-Reply-To: <201509131824.t8DIOCBc028428@envy.delorie.com>
Date: Sun, 13 Sep 2015 13:04:31 -0600
Content-Transfer-Encoding: 7bit
Message-Id: <798E233F-19D4-435C-B6E2-DC6BD352CB4E@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>
To: geda-user AT delorie DOT com
X-Mailer: Apple Mail (2.1878.6)
Reply-To: geda-user AT delorie DOT com
Errors-To: nobody AT delorie DOT com
X-Mailing-List: geda-user AT delorie DOT com
X-Unsubscribes-To: listserv AT delorie DOT com
Precedence: bulk


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.
> 

John Doty              Noqsi Aerospace, Ltd.
http://www.noqsi.com/
jpd AT noqsi DOT com