[EMAIL PROTECTED] wrote: > Does round() always perfectly return the output expected or are there > some artifacts which don't allow perfect functionality > > Using python 2.5: >>>> round(12.234, 2) > 12.23 >>>> round(12.234, 3) > 12.234 >>>> round(12.234, 1) > 12.199999999999999 > > but was expecting 12.2
http://docs.python.org/tut/node16.html > Also, for round(x,n), can't 'x' be an expression > > round(5.25/2, 2) > > was expecting 2.62 , but > >>>> round(5.25/2, 2) > 2.6299999999999999 round(x, n) essentially does the following: math.floor(x * 10**n + 0.5) / 10**n Since (5.25/2)*100 == 262.5, adding 0.5 gives 263.0 and ultimately 2.63 as the rounded number. round() does not do anything more complicated like round-to-even. Use the decimal module if you want decimal arithmetic rather than binary floating point. -- Robert Kern "I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth." -- Umberto Eco -- http://mail.python.org/mailman/listinfo/python-list
