The IEEE754 standard defines five rounding rules. The first two round to a nearest value (ties to even, ties away from zero); the others are called directed roundings: towards zero, towards positive infinity and towards negative infinity. Which one of them is used most often and why?
1
votes
1 Answers
1
votes
The most often used mode is the default mode: round to nearest, tie to even.
Why? it's only a guess but:
- minimizing the errors: directed rounding can have up to 1 ulp rounding error versus 1/2 ulp for round to nearest
- avoiding rounding bias: tie away from zero might create a bias when thousands of rounding will be chained
