• bleistift2@sopuli.xyz
      link
      fedilink
      English
      arrow-up
      23
      ·
      edit-2
      2 months ago

      That’s interesting. Obviously, you’d put a center dot to disambiguate millihertz from meter-hertz, but I can’t recall ever having learned a rule about that. So some combinations of units are inherently ambiguous?

      Also: Hz/dpt.

      • renzev@lemmy.world
        link
        fedilink
        English
        arrow-up
        17
        ·
        edit-2
        2 months ago

        I can’t tell which unit is more cursed: millihertz or meter hertz. Surely, anything that could be measured in millihertz is more natural to measure as a period, or as revolutions per minute or something, right?

        EDIT: Also, TIL about dpt. Thanks!

        A dioptre (British spelling) or diopter (American spelling), symbol dpt, is a unit of measurement with dimension of reciprocal length, equivalent to one reciprocal metre, 1 dpt = 1 m^−1.

        • Technus@lemmy.zip
          link
          fedilink
          arrow-up
          5
          ·
          2 months ago

          You know, I always figured optometry involved like, super complicated math and shit.

          Turns out it’s just basic arithmetic.

          Kinda like programming, in a way.

          • rockerface 🇺🇦@lemm.ee
            link
            fedilink
            arrow-up
            1
            ·
            2 months ago

            Yeah, from my experience ordering glasses, it’s mostly about making sure the lenses are aligned with my retinas to focus the light in the right spots. All the numbers are just a way to formalize those measurements so that the lens maker gets it right

            • Technus@lemmy.zip
              link
              fedilink
              arrow-up
              1
              ·
              2 months ago

              My last optometrist refused to tell me what my prescription was. I should have insisted, they’ve since closed up shop.

        • Eheran@lemmy.world
          link
          fedilink
          arrow-up
          3
          ·
          2 months ago

          Speed as meter per hertz is a rather odd case, like with a machine that goes in discrete steps.

          In any case, I never use implied multiplication (and others) and always simply put everything where it should be.

        • bleistift2@sopuli.xyz
          link
          fedilink
          English
          arrow-up
          3
          ·
          edit-2
          1 month ago

          TIL about dpt

          Tell me you don’t [Edit: need] glasses without telling me you don’t need glasses :D

          • renzev@lemmy.world
            link
            fedilink
            English
            arrow-up
            2
            ·
            1 month ago

            I actually do have glasses, I just never bothered learning about any of the technical details behind my lenses. Optometrist measured my eyes, I chose the cheapest frame the store offered, came back a week later to pick up the glasses and that’s about it.

    • perviouslyiner@lemmy.world
      link
      fedilink
      arrow-up
      8
      ·
      edit-2
      2 months ago

      Saw a video using mHz recently and it took way too long to realise the readout was correct and not a typo of MHz …