Comments on: 9 New Features in Ruby 2.4

By: Jesus Castello

Jesus Castello — Fri, 09 Dec 2016 13:49:23 +0000

Thank you 🙂

By: Jesus Castello

Jesus Castello — Fri, 09 Dec 2016 13:49:12 +0000

Thanks for your explanation 🙂

By: Philippe Van Eerdenbrugghe

Philippe Van Eerdenbrugghe — Fri, 09 Dec 2016 10:42:08 +0000

the reason is to prevent biasing numbers on average upward or downward.

For example if you have a list of numbers that include a lot of x.5 and you were to round all these upward, the average magnitude of the list would also shift upward. Likewise if you round downward, downward.

By rounding to the nearest even number these would balance out, given enough samples.

http://mathematica.stackexchange.com/a/2120/45178

By: Curt Sampson

Curt Sampson — Fri, 09 Dec 2016 07:41:39 +0000

It avoids “sign bias” that can make some calculations on rounded numbers head significantly away from zero compared to the same calculations on unrounded numbers or rounded versions of numbers that are very close. For example looking at the list [1.5, 2.5, 3.5, 4.5]:

The average of those numbers is 3.
The average of those numbers after rounding each towards even is 3.
If you subtract 0.00001 from each number and then round them away from zero, the average is 3.

However:
* The average of those numbers after rounding each away from zero is 3.5.

By: Ben Cullen-Kerney

Ben Cullen-Kerney — Fri, 09 Dec 2016 07:05:57 +0000

I wasn’t familiar with this rule either, until the calculator app PCalc temporarily removed it a few months ago: http://leancrew.com/all-this/2016/10/well-rounded/.