This article says that NASA uses 15 digits after the decimal point, which I’m counting as 16 in total, since that’s how we count significant digits in scientific notation. If you round pi to 3, that’s one significant digit, and if you round it to 1, that’s zero digits.

I know that 22/7 is an extremely good approximation for pi, since it’s written with 3 digits, but is accurate to almost 4 digits. Another good one is √10, which is accurate to a little over 2 digits.

I’ve heard that ‘field engineers’ used to use these approximations to save time when doing math by hand. But what field, exactly? Can anyone give examples of fields that use fewer than 16 digits? In the spirit of something like xkcd: Purity, could you rank different sciences by how many digits of pi they require?

  • pranz@lemmy.world
    1·
    1 year ago

    This probably won’t play well with this audience, but I’m a management/strategy consultant. “~5” (technically one decimal place but also rounded to the nearest interval of 5) for any C-level decks ;)

    • lolcatnip@reddthat.comEnglish
      1·
      1 year ago

      That’s less than one significant digit! Even just to one significant bit, pi is 4.

  • 𞋴𝛂𝛋𝛆@lemmy.worldEnglish
    1·
    1 year ago

    I can’t say “professionally” but I learned CAD design with FreeCAD, and know the topological naming issue thoroughly.

    Almost all “mystery” problems in CAD are due to a combination of the hacks that get around the Topological Naming Issue and π.

    In CAD, you cookie, you brownie, you might even salad, but you stay the hell away from importing π as a reference on anything complex. For 3D printing, I never need better than 0.05mm so 3.1416.

  • two_wheel2@lemm.eeEnglish
    1·
    1 year ago

    Software engineer… we also use all 16 digits of pi

  • Thurstylark@lemm.eeEnglish
    1·
    1 year ago

    Ya know, this thread has inspired me. I’m a sound engineer, and find myself yelling “check one two three four” in the michrophone to test it all the time. I’m gonna start reciting the digits of Pi instead, and then as I learn them, I’ll progressively advance how many numbers of Pi that I use in my everyday job :D

    I work at a library, though. I should probably just go with poetry or Douglas Adams or something, but this makes me sound much more impressive

  • xigoi@lemmy.sdf.org
    1·
    1 year ago

    As a mathematician, I don’t use any digits, but the symbol π.

    • Ephera@lemmy.ml
      1·
      1 year ago

      As a computer scientist, same, but it’s called PI.

      It’s the computer that does the thing with the digits, not me. 🙃

      • hallettj@leminal.spaceEnglish
        1·
        1 year ago

        In which case you’re probably using a predefined 64-bit floating point number, which I think is accurate to 15 digits.

      • xigoi@lemmy.sdf.org
        0·
        1 year ago

        I’d like to agree, but writing π with capital letters is heresy.

        • Ephera@lemmy.ml
          1·
          1 year ago

          Yeah, math conventions and programming conventions don’t always align. As in, basically never…