On May 21, 3:38 pm, Mark Dickinson <[EMAIL PROTECTED]> wrote: >>> a = 1e16-2. > >>> a > 9999999999999998.0 > >>> a+0.999 # gives expected result > 9999999999999998.0 > >>> a+0.9999 # doesn't round correctly. > > 10000000000000000.0
Notice that 1e16-1 doesn't exist in IEEE double precision: 1e16-2 == 0x1.1c37937e07fffp+53 1e16 == 0x1.1c37937e08p+53 (that is, the hex representation ends with "7fff", then goes to "8000"). So, it's just rounding. It could go up, to 1e16, or down, to 1e16-2. This is not a bug, it's a feature. -- http://mail.python.org/mailman/listinfo/python-list
