What field do you work in, and how many digits of pi do you use?

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?

ada,
@ada@lemmy.blahaj.zone avatar

I’m Australian. I normally manage a pie with 5 digits, unless it’s particularly crumbly or runny, in which case I will sometimes use 10!

kleiner_zeh,

3628800?? thats a lot!

Hegar,

I find this comment absolutely hilarious.

I recognize your profile pic from a comment months back that was also a short, deadpan reinterpretation of the question that I found hilarious. I can't for the life of me remember what it was of course.

Thanks for making me laugh!

ada,
@ada@lemmy.blahaj.zone avatar

I’ll be here all year :P

livus,
livus avatar

I bet all the Americans reading this are now imagining you eating some gooey dessert like key lime pie or pumpkin pie with your hands.

BlueEther,
@BlueEther@no.lastname.nz avatar

If it’s anything like the little island off it’s east coast it will be steak and black pepper of a chicken korma pie

ada,
@ada@lemmy.blahaj.zone avatar

Steak and black pepper pie, now that’s what I’m talking about!

livus,
livus avatar

Peppersteak and Tomato ftw.

Hegar,

Chilli beef and cheese from a servo or gtfo.

BlueEther,
@BlueEther@no.lastname.nz avatar

I often find chilli beef on the dry side, I guess that it would mean that that pie may need only 5 digits and not the full 10 of a juicy steak pie

Hegar,

With cheese inside its a sloppy mess and often requires the full 10. Though tbh I haven't lived in Australia for 10 years or eaten meat in 20, so I wouldn't listen to anything I have to say about pies.

livus,
livus avatar

Fraser Island? Or Tasmania?

BlueEther,
@BlueEther@no.lastname.nz avatar

The ones slightly larger that tasmania…

livus,
livus avatar

Sacrilege!

Firstly 1, 500 km away is not coastal (if it was then the UK is an island off the coast of Iceland).

Secondly if anyone is off anyone else's coast it's the west island which is off our coast, not the other way round.

BlueEther,
@BlueEther@no.lastname.nz avatar

true enough

livus,
livus avatar

You're right about the pies but.

BigDanishGuy,

Embedded engineer, working in education. I use 3 for mental estimations and whatever is stored in the calculator, I have happened to grab, for “precision” work. Sometimes I’ll even round pi to 4, to build in some tolerance when calculating materials.

RvTV95XBeo,

Mechanical engineer here - Matlab uses 16 digits for pi(), so that’s my go-to. When doing some larger thermodynamic simulations, I sacrifice some digits of pi to get more computational headroom. But that’s only after I get really annoyed at the code, and it almost never helps (but rarely hurts, as well)

Pulptastic,

Well, I have two answers. If it is mental math I use 3.1 and round up. If I am calculating something I care about I use my TI-86 which has pi to 14 digits.

Practically speaking, I don’t often need to convert diameter to circumference but I do occasionally need to calculate area or volume and in those cases I have way more error in other measurements or assumptions (2 or 3 digits) so 5 digits of pi is more than enough.

dutchkimble,

So you round up 3.1 to 3.2?

Pulptastic,

No I round the result to compensate for the error.

TheRealKuni,

Back in middle school I memorized this much of pi (for no good reason):

3.14159265358979323846264338327950288419716939937510

That’s far more accurate than I’ll ever need.

chayleaf,

I’m a programmer and I remember 33 digits, but in practice I never use pi because I never have to deal with geometry

josefo,

Game programmer here, lots of geometry. Usually 16 digits after the dot is ok. In graphics programming is also useful to define and use Tau (π×2), also defined to 16 digits

HEXN3T,
@HEXN3T@lemmy.blahaj.zone avatar

I’m a nothing in particular, and I used to remember 100 digits. I could probably remember again in an hour.

letsgo,

I’m British, not American, so I use 7/22.

eatham,
@eatham@aussie.zone avatar
eatham,
@eatham@aussie.zone avatar
eatham,
@eatham@aussie.zone avatar
Saigonauticon,

Prototyping. I just checked and my slide rule has a notch for pi. So, all of them.

nycki,

But how many digits of the result do you use?

Saigonauticon,

None of them! Numbers are a poor way to communicate with most of my clients.

On the rare exception, it depends on the number of significant digits of the measurement I (for example) multiply it with. Digits past that don’t communicate any useful information.

MissJinx,
@MissJinx@lemmy.world avatar

I’m an auditor. Zero digits is the norm if I have to use Pi there is something VERY wrong

pelletbucket,
@pelletbucket@lemm.ee avatar

baker. I measure pie based on how much I can fit in my mouth

RIP_Cheems, (edited )
@RIP_Cheems@lemmy.world avatar

Mechatronics student. If your not using 3.1416 at a minimum, then your doing it wrong.

TIMMAY,

you’re

eatham,
@eatham@aussie.zone avatar

doing it wrong

TomAwsm,

then

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