Re: gEDA-user: pcb crooked traces

[John Doty <jpd@xxxxxxxxx>]

On Oct 8, 2010, at 3:04 PM, Karl Hammar wrote:

> So, in what way are floats worse than ints (I'm talking about 
> representaion, not about performance) and why could we not "reasonably 
> use floating-point"?

The problem is that in engineering documentation, dimensions are generally given as decimal fractions of inches or meters. Cumulative roundoff error can be avoided if the numeric encoding can exactly represent such numbers. Scaled integers or scaled floating point may be used, but scaled integers are a bit easier to use and understand, and are usually more efficient. Unscaled binary floating point is troublesome because it cannot exactly represent most decimal fractions, so it is prone to cumulative error.

John Doty              Noqsi Aerospace, Ltd.
http://www.noqsi.com/
jpd@xxxxxxxxx




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