Thanks for the clarification, but how is the numpy rounding directed? Round to nearest, ties to even? http://en.wikipedia.org/wiki/IEEE_floating_point#Rounding_rules Just curious, as I couldn't find a reference.
- Ray At 07:44 AM 7/27/2014, you wrote: >On Sun, Jul 27, 2014 at 3:16 PM, RayS <r...@blue-cove.com> wrote: > > At 02:04 AM 7/27/2014, you wrote: > > > >>You won't be able to do it by accident or omission or a lack of > >>discipline. It's not a tempting public target like, say, np.seterr(). > > > > BTW, why not throw an overflow error in the large float32 sum() case? > > Is it too expensive to check while accumulating? > >In the example that started this thread, there's no overflow (in the >technical sense) occurring. Overflow for ints means wrapping around, >and for floats it means exceeding the maximum possible value and >overflowing to infinity. > >The problem here is that when summing up the values, the sum gets >large enough that after rounding, x + 1 = x and the sum stops >increasing. (For float32's all this requires is x > 16777216.) So >while the final error is massive, the mechanism is just ordinary >floating-point round-off error. > >-n > >-- >Nathaniel J. Smith >Postdoctoral researcher - Informatics - University of Edinburgh >http://vorpus.org >_______________________________________________ >NumPy-Discussion mailing list >NumPy-Discussion@scipy.org >http://mail.scipy.org/mailman/listinfo/numpy-discussion _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
