Stefan van der Walt wrote: > For some reason, the kahan_sum of [0.2,0.0,0.8,0.0] is ever so > slightly larger than 1.0 (in the order of 1e-16), but I'm not sure > why, yet (this isn't specific to kahan summation -- normal summation > shows the same behavior).
Just to make sure -- is the khan_sum "compensated summation"? Is the kahan_sum closer? -- it should be, though compensated summation is really for adding LOTS of numbers, for 4, it's pointless at best. Anyway, binary floating point has its errors, and compensated summation can help, but it's still not exact for numbers that can't be exactly represented by binary. i.e. if your result is within 15 decimal digits of the exact result, that's as good as it gets. -Chris -- 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 [EMAIL PROTECTED] _______________________________________________ Numpy-discussion mailing list [email protected] http://projects.scipy.org/mailman/listinfo/numpy-discussion
