delorie.com/archives/browse.cgi   search  
Mail Archives: geda-user/2016/01/06/07:01:19

X-Authentication-Warning: delorie.com: mail set sender to geda-user-bounces using -f
X-Recipient: geda-user AT delorie DOT com
X-TCPREMOTEIP: 63.119.35.194
X-Authenticated-UID: jpd AT noqsi DOT com
Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\))
Subject: Re: [geda-user] Re: some more geometry module tweaks (sorry, wall of text)
X-Pgp-Agent: GPGMail 2.5.2
From: John Doty <jpd AT noqsi DOT com>
In-Reply-To: <alpine.DEB.2.00.1601060519350.9035@igor2priv>
Date: Wed, 6 Jan 2016 07:00:54 -0500
Message-Id: <3FD00F19-8C76-4825-B001-0341507C1212@noqsi.com>
References: <CAC4O8c-n4cHWum2MUzgDw=NLuKPK395xp_F24cSyoXhnADRskw AT mail DOT gmail DOT com> <alpine DOT DEB DOT 2 DOT 00 DOT 1512230503390 DOT 9035 AT igor2priv> <CAC4O8c8A271d5unQWRV=PoaEsJECgZt33Wy16uCnK6D+4LCzww AT mail DOT gmail DOT com> <alpine DOT DEB DOT 2 DOT 00 DOT 1512260402081 DOT 9035 AT igor2priv> <CAC4O8c-49Fn191KT-p0hXi1jXW=OeTSaNUh11pLmBQYHeGtyoA AT mail DOT gmail DOT com> <alpine DOT DEB DOT 2 DOT 00 DOT 1512310512510 DOT 9035 AT igor2priv> <CAC4O8c8Or1FS=x18C7Zv5uu+dUOXX2My4K+njsoufNeotm_CBQ AT mail DOT gmail DOT com> <alpine DOT DEB DOT 2 DOT 00 DOT 1601060519350 DOT 9035 AT igor2priv>
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

--Apple-Mail=_83C1D5C9-E774-496A-B3A6-7D3D61CF3A1E
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain;
	charset=windows-1252


On Jan 5, 2016, at 11:53 PM, gedau AT igor2 DOT repo DOT hu wrote:

>=20
>=20
> On Tue, 5 Jan 2016, Britton Kerin (britton DOT kerin AT gmail DOT com) [via =
geda-user AT delorie DOT com] wrote:
>=20
>>=20
>> Igor and I have been discussing pcb geometry kernel design, I'm ccing =
the
>> list in case anyone has strong opinions.
>>=20
>> [snip]
>>=20
>>     Question is: should a big geometry refactoring fix old bugs or
>>     questionalbe numeric conversions or just do the same thing with
>>     different code org?
>>=20
>>     For all the time, I assumed the first.
>>=20
>>=20
>> I agree, but we may have different ideas of what the fix would be.  =
If you
>> want to stop using floating point entirely, it's a huge effort, and =
ints
>> won't do what you want either, you need rationals.  If by fix you =
mean
>=20
> Although later part of the mail had a list like this, that doesn't =
include rationals so I'll repeat it for those who didn't have the chance =
to follow our conversation. The options I currently see:
>=20
> 1. go for maximal precision, be theoretically/mathematically correct =
in all situations, no rounding ever: rationals.

There=92s a catch, though. You can have rational translations or =
rational rotations, but not both. If you base your allowed rotations on =
the angles in triangles whose sides are Pythagorean triples you can =
represent them with rational rotation matrices. However, neat rational =
fractions of a right angle don=92t have associated Pythagorean triples =
(Euclid famously showed this for 45 degrees).

I might try the Pythagorean route if I was doing this, but maybe more =
because it looks interesting rather than for practicality.

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



--Apple-Mail=_83C1D5C9-E774-496A-B3A6-7D3D61CF3A1E
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
	filename=signature.asc
Content-Type: application/pgp-signature;
	name=signature.asc
Content-Description: Message signed with OpenPGP using GPGMail

-----BEGIN PGP SIGNATURE-----
Comment: GPGTools - https://gpgtools.org
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=jqI+
-----END PGP SIGNATURE-----

--Apple-Mail=_83C1D5C9-E774-496A-B3A6-7D3D61CF3A1E--

- Raw text -


  webmaster     delorie software   privacy  
  Copyright © 2019   by DJ Delorie     Updated Jul 2019