Dan Bishop wrote: > That's A source of error, but it's only part of the story. The > double-precision binary representation of 0.039 is 5620492334958379 * > 2**(-57), which is in error by 1/18014398509481984000. By contrast, > Johnny Lee's answer is in error by 9/262144000, which is more than 618 > billion times the error of simply representing 0.039 in floating point > -- a loss of 39 bits. > > The problem here is catastrophic cancellation. > > 1130748744.500 ~= 4742703982051328 * 2**(-22) > 1130748744.461 ~= 4742703981887750 * 2**(-22) > > Subtracting gives 163578 * 2**(-22), which has only 18 significant bits. >
Hmm. Good point. -- http://mail.python.org/mailman/listinfo/python-list
