Everything Is Logarithms

(alexkritchevsky.com)

66 points | by E-Reverance 2 hours ago

5 comments

  • helterskelter 8 minutes ago
    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.
    • badlibrarian 3 minutes ago
      The physical version of that magic wormhole is called a slide rule.
  • badlibrarian 39 minutes ago
    This essay needs a type system. Every time it says “log” it should say: log of what, into what?

    It’s like audio where people say "dB" as if it answers the next question. Relative to what, measured how, and weighted for whom?

    Author should brush up on https://en.wikipedia.org/wiki/Lie_theory

    • jmyeet 24 minutes ago
      The first section details how the author thinks of "log N" with no base as an abstract object rather than a number. Or what are you referring to?
      • badlibrarian 13 minutes ago
        The first section is the good part.

        The later reuse of “log” across valuations, dimension, vector fields, orders of vanishing is not so good. Those may be related ideas, but each needs a type signature: from what, to what, and preserving which operation?

  • amelius 23 minutes ago
    Does this answer the question of why we see hyperoperations until exponentiation in physics, but not higher?
  • jongjong 28 minutes ago
    That's a lot of ways to think about logarithms.

    Logarithms are laughably simple once you've fully internalized the meaning of the log function; it simply answers the question:

    "To what power must I raise the base to get the argument?"

    This is why the output tapers out as you increase the argument; because as the argument grows exponentially, you only need a fixed increment in the power to reach that number... So if you increase the argument only by a fixed amount (linearly), then the output will grow sub-linearly.

    I remember when I was doing algebra with logs many years ago at school, I was applying rules to remove the log from one side of the equation.

    Then when I got to uni, I had to revise the rules but it was kind of silly of me because those rules can be trivially derived if you just think about what the log function means. Turns out I had been solving equations with logs throughout school without understanding what they even meant... It's only at university that I actually bothered to learn them.

    Actually TBH. I didn't even fully understand powers even though I was doing calculus with them at school. I only fully understood powers once I properly internalized the concept of k-ary trees as a proxy.

  • yaccb3 1 hour ago
    [dead]