On 09/12/2013 09:17 AM, Dmitry Nadezhin wrote: > The patch is correct when decimal ULP of kept digits is pow(10,-1075) > of less. pow(2,53) has 17 decimal decimal digits. MAX_NDIGITS = 1100 > > 1075 + 17 .
OK. That makes more sense. Can we please add the short comment in the code (maybe next time around)? I expected to see something like "The value below is chosen as the conservative threshold. We can demonstrate (<link>) that decimal ulp should be less than 10^(-1075) to guarantee correctness; we also compensate for binary mantissa which takes 53 binary digits, or 17 decimal ones. Hence, 1075+17 =~ 1100." -Aleksey.
