Thread

1. miffy900 · 1789683723 · focus · HN ↗

   I really wish people would stop saying N times smaller than something when making a comparison; that makes no sense - it's 1/9th (11.11%) the size. You don't get a smaller quantity by multiplying by a number greater than 1.0. You could instead reverse the subjects being compared - "the original model is 9x bigger than this new smaller, efficient model" or some such. That makes sense.

   I keep seeing this being used when people talk about efficiency or performance gains and it's just very unintuitive language.

   1. DoctorOetker · 1789744278 · focus · HN ↗

      Define the "parallel sum"

      a∥b=((a*b)/(a+b)

      A normal sum has the associative property:

      a+(b+c)=(a+b)+c which justifies dropping the parentheses

      a+(b+c)=a+b+c=(a+b)+c

      It is just an exercise for the reader that the parallel sum ∥ operation is associative:

      a∥(b∥c) = (a∥b)∥c

      multiplication is typically defined as repeatedly adding:

      a x b = b+b+...+b+b (a times b)

      similarily one can define parallel multiplication xx :

      a xx b = b∥b∥...∥b∥b (a parallel-times b)

      The reader can verify that 9 parallel-times size

      9 xx size = size∥size∥size∥size∥size∥size∥size∥size∥size = size / 9

      So I just think the Bonsai designers meant it was 9 parallel-times smaller, which checks out...

      x∥x=(xx)/(x+x)= x/2

      x∥x∥x =(x/2x)/(2/x+x)=(x/2)/(3/2)=x/3

      x∥x∥x∥x = x/4

Unofficial Hacker News client; not affiliated with Y Combinator.