Asklemmy

43896 readers

936 users here now

A loosely moderated place to ask open-ended questions

Search asklemmy 🔍

If your post meets the following criteria, it's welcome here!

Open-ended question
Not offensive: at this point, we do not have the bandwidth to moderate overtly political discussions. Assume best intent and be excellent to each other.
Not regarding using or support for Lemmy: context, see the list of support communities and tools for finding communities below
Not ad nauseam inducing: please make sure it is a question that would be new to most members
An actual topic of discussion

Looking for support?

Looking for a community?

Lemmyverse: community search
sub.rehab: maps old subreddits to fediverse options, marks official as such
[email protected]: a community for finding communities

~Icon~ ~by~ ~@Double_[email protected]~

founded 5 years ago

MODERATORS

[email protected]

129

What field do you work in, and how many digits of pi do you use? (lemmy.world)

submitted 8 months ago by [email protected] to c/[email protected]

125 comments fedilink hide all child comments

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?

you are viewing a single comment's thread
view the rest of the comments

[–] [email protected] 6 points 8 months ago* (last edited 8 months ago) (2 children)

Yes, it's technically correct (which we all know is the best kind of correct) and engineers would understand.

Using mm means most everyone (who knows metric) understands that in much more practical terms. A quarter of a tenth of thiiis much is a pretty damn tight fit.

[–] [email protected] 5 points 8 months ago

Micrometers is actually so common that it has a colloquial non-SI name of "micron"

According to wiki:

The micrometre is a common unit of measurement for wavelengths of infrared radiation as well as sizes of biological cells and bacteria,[1] and for grading wool by the diameter of the fibres.[3] The width of a single human hair ranges from approximately 20 to 200 μm.

[–] [email protected] -3 points 8 months ago (1 children)

Bold of you to assume that anywhere close to everyone who understands metric would know that 0.25 is a quarter of something.

[–] [email protected] -1 points 8 months ago (1 children)

Bold of you to assume that the country that still uses the Imperial system is the one that better understands fractions.

https://www.cbc.ca/radio/undertheinfluence/how-failing-at-fractions-saved-the-quarter-pounder-1.5979468

[–] [email protected] -1 points 8 months ago

I didn't say that imperial countries understand them better.