Doesn't Python do rounding based on the binary representation of the float?
I'm a little confused what "round to even" means in that case. Aaron Meurer On Wed, Apr 10, 2019 at 6:16 PM Chris Smith <smi...@gmail.com> wrote: > > Python 3 implements "round to even on tie" logic so `round(12.5)` -> 12, not > 13. I have updated, in #16608, the round function but there is a difference > in how ties are detected. I shift the desired position to the ones position > and then check for a tie so 12.345 is shifted to 1234.5 and rounded to 1234 > then is divided by 100 to give 12.34. Python doesn't do this. I suspect it > adds 0.05 and then detects that12.395 > 12395/1000 and rounds up to 12.35 > > > >>> Rational(*.345.as_integer_ratio())-Rational(345,1000) # .345 < 345/1000 > -3/112589990684262400 > >>> Rational(*.395.as_integer_ratio())-Rational(395,1000) # .395 > 395/1000 > 1/56294995342131200 > > > >>> round(12.345,2) # 12.345 rounds up b/c a tie is not detected > 12.35 > > > > Does anyone have objections to the proposed rounding? > > /c > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sympy+unsubscr...@googlegroups.com. > To post to this group, send email to sympy@googlegroups.com. > Visit this group at https://groups.google.com/group/sympy. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/a84085c6-aa90-437c-b063-a87f909beac4%40googlegroups.com. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To post to this group, send email to sympy@googlegroups.com. Visit this group at https://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAKgW%3D6K2Y%3D6ZonewE2_EeX5rjpBP3L4TVBMw8cr_iF27T6PArA%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
