Serhiy Storchaka <storchaka+cpyt...@gmail.com> added the comment: This is the result of multiple roundings.
0.9 and 0.1 can't be represented exactly as floats. They are approximated by binary fractions. >>> from fractions import Fraction >>> Fraction(0.9) Fraction(8106479329266893, 9007199254740992) >>> Fraction(0.1) Fraction(3602879701896397, 36028797018963968) The result of the division of these fractions can't be represented as a float too. >>> Fraction(0.9)/Fraction(0.1) Fraction(32425917317067572, 3602879701896397) >>> Fraction(0.9)/Fraction(0.1) - 9 Fraction(-1, 3602879701896397) >>> float(Fraction(0.9)/Fraction(0.1) - 9) -2.7755575615628914e-16 >>> 9 + float(Fraction(0.9)/Fraction(0.1) - 9) 9.0 It is slightly smaller than 9, but the nearest float value is 9.0. Thus the result of the division is rounded up to 9.0. A similar issue already was opened several months ago. I don't remember the number. ---------- nosy: +serhiy.storchaka resolution: -> not a bug stage: -> resolved status: open -> closed _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue32543> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
