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.

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badlibrarian 2 hours ago | parent | next [-]

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

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eager_learner 2 hours ago | parent | prev [-]

care to share the name of the said book?

	▲	helterskelter 2 hours ago \| parent [-]
		Trigonometry for Navigating Officers by WP Winter https://www.google.com/books/edition/Trigonometry_for_Naviga... I found this book because I was a little rusty on my trig and most celestial navigation texts will just throw the PZX equation (and others) at you without breaking down what's actually being done with it on a mathematical level...it's just kind of treated like a magical black box without any discussion, and I'd rather have a complete understanding of what I'm doing and why. Having an application-specific approach also makes it a lot easier to learn. I'm using it with Norie's Nautical Tables, which has the log tables and a whole lot else: https://bluewaterweb.com/product/nories-nautical-tables-2025... I'm sure there are plenty of free PDF's of log tables you can find though. (I believe they used log tables on boats primarily because it's easier to use than a slide rule when everything is constantly rocking back and forth.)