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helterskelteryesterday at 11:10 PM4 repliesview on HN

Logs are awesome. I started a math textbook from the 1920's a while ago, and all the calculations relied on tabulated logs, where you would convert the number to a log in a table to reduce the operation's degree, then convert back to the ordinary representation. This would reduce operations like finding cubed roots to division, would could be converted to log-log to be further reduced to subtraction before you would restore to ordinary notation. It feels like you're using a magic wormhole or something when you're doing this stuff by hand, it's really neat.


Replies

badlibrarianyesterday at 11:15 PM

The physical version of that magic wormhole is called a slide rule.

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all2today at 3:01 AM

Got a PDF? I love old books like this.

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eager_learneryesterday at 11:22 PM

care to share the name of the said book?

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porridgeraisintoday at 11:13 AM

Yep, we used manual math + some log tables for calculations in our school exams as late as last decade. Since calculators were not allowed. The exam would be such that you would need the log tables once or twice over the course of the exam. Example: dividing = lookup(a)-lookup(b) and then lookup that in the inverse log (i.e exp) tables.