It would be useful when we need to subtracting a bit before comparing by greater or less. By subtracting a bit, we only have an absolute error tolerance and with the new functions, we can have both absolute and relative error tolerance. This is how isclose(a, b) better than abs(a-b)<=atol.
2015-10-19 15:46 GMT-04:00 Chris Barker <chris.bar...@noaa.gov>: > > > On Mon, Oct 19, 2015 at 3:06 AM, cy18 <thec...@gmail.com> wrote: > >> I think these would be useful and easy to implement. >> >> greater_close(a, b) = greater_equal(a, b) | isclose(a, b) >> less_close(a, b) = less_equal(a, b) | isclose(a, b) >> greater_no_close = greater(a, b) & ~isclose(a, b) >> less_no_close = less(a, b) & ~isclose(a, b) >> > > What's the use-case here? we need is_close because we want to test > equality, but precision errors are such that two floats may be as close to > equal as they can be given the computations done. And the assumption is > that you don't care about the precision to the point you specify. > > But for a greater_than (or equiv) comparison, if you the precision is not > important beyond a certain level, then it's generally not important whether > you get greater than or less than when it's that close.... > > And this would great a wierd property that some values would be greater > than, less than, and equal to a target value -- pretty weird! > > note that you can get the same effect by subtracting a bit from your > comparison value for a greater than check... > > But maybe there is a common use-case that I'm not thinking of.. > > -CHB > > -- > > Christopher Barker, Ph.D. > Oceanographer > > Emergency Response Division > NOAA/NOS/OR&R (206) 526-6959 voice > 7600 Sand Point Way NE (206) 526-6329 fax > Seattle, WA 98115 (206) 526-6317 main reception > > chris.bar...@noaa.gov > > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > https://mail.scipy.org/mailman/listinfo/numpy-discussion > >
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