On Fri, Jan 29, 2010 at 10:50 AM, Peter Clifton <[email protected]> wrote: > On Fri, 2010-01-29 at 09:00 -0600, Mark Rages wrote: > >> Assuming: largest arc is 24 inches, and the desired precision 1e-5 inches. > > A gentle very gentle curve would require more, but certainly the above > would be large enough for most of the applications I've seen for PCBs > which have rotational symmetry. > > Arguably we can get away with quite a bit less precision for large > geometry parts. 1e-4" would probably be fine, if not 1e-3". > >> Then the precision of the smallest angle is (1e-5)/24 radians or >> 2.38*10-5 degrees. To be safe, the new units should be millionths of >> a degree, so one revolution is 360000000. Sounds good? Or a > > The maximum of a 32bit (signed) integer is: > > 2147483647 > 360000000 > > So that wouldn't have an issue representing the number. > >> double-precision floating-point would maintain more than sufficient >> accuracy over the (0,360] range. > > Try to avoid floating point for storage.
Why? I can probably find a i487 processor for you if you need one ;) Seriously, why? all programming languages from C on up have facilities to parse and write floating point. And it makes the file more human-readable, because you don't have to do mental arithmetic to understand a measurement. Regards, Mark markra...@gmail -- Mark Rages, Engineer Midwest Telecine LLC [email protected] _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
