• nLuLukna @sh.itjust.works
    link
    fedilink
    arrow-up
    25
    arrow-down
    2
    ·
    edit-2
    1 year ago

    Pemdas isn’t as arbitrary as people in this thread think it is.

    I love maths, and I’m going to butcher any attempt to explain why pemdas isnt totally random. But you can look it up if you wanna know more I guess

    Besides no one ever uses that notation - by the time you learn about quadratics, you leave multiplication symbols out of the equation entirely and much of the notation changes shape, with division exclusively being expressed as negative powers or fractions.

    At that point you aren’t going to make mistakes, since each hyperlevel uses a different style of notation. Pemdas is used to teach 4 year olds, and it’s fucking dumb. What happens with a log, or sine function. Don’t even get me started on integrals and derivatives.

    Pemdas is shit, but not because it’s abirtary. In fact it’s shit because it’s a shithole acyromn

    • Uphillbothways@lemmy.world
      link
      fedilink
      arrow-up
      13
      arrow-down
      1
      ·
      edit-2
      1 year ago

      Pemdas is mostly just factoring, kinda. That’s how you should think of it.

      2x4 is really 2+2+2+2.

      That first 2+(anything else) can’t be acted/operated upon until you’ve resolved more nested operations down to a comparable level.

      That’s it. It’s not arbitrary. It’s not magic. It’s just doing similar actions at the same time in a meaningful way. It’s just factoring the activities.

      • Kogasa@programming.dev
        link
        fedilink
        arrow-up
        7
        arrow-down
        19
        ·
        1 year ago

        It is, in fact, completely arbitrary. There is no reason why we should read 1+2*3 as 1 + (2*3) instead of (1 + 2) * 3 except that it is conventional and having a covention facilitates communication. No, it has nothing to do with set theory or mathematical foundations. It is literally just a notational convention, and not the only one that is still currently used.

        • Uphillbothways@lemmy.world
          link
          fedilink
          arrow-up
          11
          ·
          edit-2
          1 year ago

          If you don’t accept adding and subtracting numbers as allowed mathematical transactions, multiplication doesn’t make sense at all. It isn’t arbitrary. It’s fundamental basic accounting.

          • Kogasa@programming.dev
            link
            fedilink
            arrow-up
            0
            arrow-down
            2
            ·
            edit-2
            1 year ago

            What you just said is at best irrelevant and at worst meaningless. No, the fact that multiplication is defined in terms of addition does not mean that it is required or natural to evaluate multiplication before addition when parsing a mathematical expression. The latter is a purely syntactic convention. It is arbitrary. It isn’t “accounting.”

        • nLuLukna @sh.itjust.works
          link
          fedilink
          arrow-up
          5
          ·
          edit-2
          1 year ago

          Yeah I haven no idea what I was saying when I said that, I’ve edited my comment a bit.

          On that note though using your example I think I can illistarte the point I was trying to make earlier.

          1 + (2*3) by always doing multiplication first we can remove those brackets.

          (1 + 2) * 3 can be rewritten as (1 * 3 )+ (2 * 3) so using the first rule again makes a sense. That is a crappy explaination but I think you get my gist.

          • Kogasa@programming.dev
            link
            fedilink
            arrow-up
            0
            arrow-down
            2
            ·
            1 year ago

            Your point is not clear.

            1 + (2 * 3) by always doing addition first we can remove those brackets.

            (1 * 3) + (2 * 3) can be rewritten as (1 + 2) * 3 so using the first rule again makes sense.

            Do you see the issue?

            • nLuLukna @sh.itjust.works
              link
              fedilink
              arrow-up
              1
              ·
              1 year ago

              I don’t see it mate. So you’re going to have to tell me, sorry.

              The point I’m trying to make is that using Pemdas/Bedmas is the most effiecent way of removing brackets - I actually don’t 100% know that but I doubt it creates hundreds of brackets - if thats slightly clearer.

              • Kogasa@programming.dev
                link
                fedilink
                arrow-up
                1
                ·
                1 year ago

                I don’t know how else to explain it. I used your own argument verbatim but with the opposite assumption, that addition takes priority over multiplication. In either case, some expressions can be written without parentheses which require parentheses in the other case.

                • nLuLukna @sh.itjust.works
                  link
                  fedilink
                  arrow-up
                  1
                  ·
                  1 year ago

                  Right well that makes sense. And is also a very good point. I don’t really see why you couldn’t do that. So I guess it is arbitrary. Although you then have the question of which case occurs more commonly, which is imo actually quite interesting, but also entirely pointless, since good luck showing one case to be more than the other. It’s like that door and wheel question.