• bleistift2@sopuli.xyz
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    3 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
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      3 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
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        3 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
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          3 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
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            3 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
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        3 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
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        3 months ago

        TIL about dpt

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

        • renzev@lemmy.world
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          3 months 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.