tom wrote: > On Wed, 23 Feb 2005 19:04:47 -0600, Andy Leszczynski wrote: > > > It is on Windows, Linux, Python 2.3: > > > > [GCC 3.3.2 (Mandrake Linux 10.0 3.3.2-6mdk)] on linux2 Type "help", > > "copyright", "credits" or "license" for more information. > > >>> a=1.1 > > >>> a > > 1.1000000000000001 ... > > Is it normal? > > Yes. Quite normal. ... > The print statement ,by itself, adds the most minimial formatting, which > amounts to dropping the last significant digit your math processor holds. > That last digit will *always* contain some arithmetic slop.
Your statement is misleading, because it suggests that your processor stores digits. It doesn't; it stores *bits*. The distinction is important because 1.1 does not have a finite representation in binary. Instead, it's the repeating bit sequence 1.0 0011 0011 0011... This is analogous to 1/3 = 0.333... in base ten. IEEE 754 requires that all normalized numbers be rounded to 53 significant bits, so "1.1" is actually stored as 0x1.199999999999A, which is equivalent to the decimal number 1.100000000000000088817841970012523233890533447265625. Python's repr function rounds this to 17 significant digits, or "1.1000000000000001". -- http://mail.python.org/mailman/listinfo/python-list
