Peter Todd wrote:

>> All CAD where I've looked into this use an integer representation that is a
>> sub-multiple of both mm and mil.

Can that work? What base unit would that be? I don't think such a number
exists.

> Using 0.1mm as your base unit would do you just fine as the inch is
> defined as exactly 25.4mm.

/If/ you use a metric base unit -- because the inch is defined based on a
metric unit, as you say. That's why conversions from inch to metric units
always result in numbers with a limited (and easy to determine) number of
decimals: the conversions are multiplications.

You're in more trouble if you're using a base unit defined in inches. Then
the conversions become divisions, with the problems Tomas mentioned.

Gerhard

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist