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Re: gEDA-user: pcb crooked traces



At 04:22 AM 10/9/2010, you wrote:
Rick Collins wrote:
Yes, it is about tolerance... and error. How much error will be introduced into a design if the system rounds all metric measurements to 0.01 mils? How much tolerance is acceptable? When you can answer these two questions for all designs and all users you can't expect anyone to believe this is "nonsense"! If you have a connector, for example, with 100 pins spaced on metric centers, the accumulated error can approach a half mil or 0.0127 mm. That may be a significant fraction of the pin spacing and likely not a good idea. Larger connectors would have more accumulated error.
While accumulation of error is an issue with floating point, the connector or any predefined
shape is a particularely bad example:
At least I wouln't convert the spacing and then sum up the erratic value but convert all the original values, which gives exactly 1 conversion error per position, irrespective of the number of pins/position. And that's exactly how the read routines operate. To do it the wrong way, they would need to be fortune tellers, because there is
no 'array' element in new-lib files.

Then please come up with some of your own. I am sure there is no shortage of examples just because I haven't thought of them.

Rick



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