On Mon, 07 Feb 2011 13:30:24 -0500 rickman <[email protected]> wrote:
> On 2/7/2011 11:21 AM, Peter C.J. Clifton wrote: > > On Feb 7 2011, rickman wrote: > > > >> The real question is does the current method cause any problems? > >> When this was discussed a few months ago the answer was "no". So > >> why worry about 1 part in a million error? Engineering is all > >> about tolerances. > > > > We do have some problems with rounding and 45-degree lines, but I'm > > not convinced metric units internally is a magic bullet for that. > > > > Display of accurate coordinate in metric IS a problem though. > > How so? I thought the dimensions in these tools are done with 10 > microinch resolution. Isn't that enough for anything on the visible > horizon? Actually, I wouldn't think the display is the problem, but > rather the problem would be generation of rounded data for output > such as Gerber files. What are people using this software for that > requires better than 10 millionths of an inch accuracy? I often see some odd values due to inexact conversion to millimeters in pcb. It slows me down when I'm trying to draw a footprint since I have to constantly round the numbers in my head; while easy, you have to be constantly doing this every time you click a point and it is a waste of time. See a simple example on the screen shot: <http://gibibit.com/upload/2011-02-07_pcb_mm_error_display.png>. Here I used the "measure" tool to measure a distance between two points on a 0.5 mm grid, but the displayed result is not correct. Sure, mathematically it is extremely close to the correct value, but for my brain to convert this each time I glance at the position/measurement display in pcb, it does accumulate since I refer to the display so frequently. Regards, Colin _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
