Talk:Safe addition

Wouldn't the sum of the two ranges be (a+↓b, a+↑b)? Modulo whether they are closed or open bounds, of course (my argument doesn't depend on that). I can't see any logical reason for assuming otherwise, as the “real” values of a and b could be anywhere from the lower bound to the upper bound; that's got to be what the range means, with appropriate infinitesimals in the open bound case, of course. (Yes, this does mean that the error will increase as more operations are performed; this is a normal feature of calculations with physical quantities if I'm remembering my Physics-101 class right.) —Donal Fellows 22:52, 18 August 2009 (UTC)