Hacker News Reader

Comment by cbm-vic-20 | Hacker News Reader

Not directly related to the linked content, but "N times less" never really made that much sense to me. In this case, I'm guessing "5x reduction" means "80% less"? Or "20% of the previous usage"?

View on HN

N times less usually just means it uses 1/N. So this would mean it uses only 20% of the memory it used originally.

Yeah it doesn’t make sense as the x in 5x I would have thought repetesents a multiplication rather than (divide)

It would make more sense for me to say a fifth, or 1/5

    log(5x)  =  log(5) + log(x)
    log(x/5) = -log(5) + log(x)

So the difference is just a sign change on a log scale. And it's natural to use a log scale when working with percentage changes.

Natural for who?

Perhaps better expressed as “5 fold”.

"We went from 1400KB of RAM per repo to 310KB with no measurable latency changes."

So, not exactly, but close. ~22% of previous usage.

Yes that is correct. It's not always the most intuitive language.

5 times less than 20 would be 4 or (20 * 1/5), the same as 20 is 5 times more than 4.

Yes it is the marketing speak of 80% less. And generally speaking works much better than percentage.

I saw advertisements "now 20% cheaper!", while price change (original->new) was 30€->25€.

Marketing always finds a way.. 5/30=16.6%, 5/25=20%

Reply on news.ycombinator.com