Comment by vel0city
4 days ago
If I ask for someone for 3 of something and they give me 3.001 of it, it's whatever. If I ask someone for 3.000 of something and they give me 3.001 of it, it's out of spec.
4 days ago
If I ask for someone for 3 of something and they give me 3.001 of it, it's whatever. If I ask someone for 3.000 of something and they give me 3.001 of it, it's out of spec.
Admittedly I only did this in school and it's been over 10 years, but I recall when doing engineering drawings, we'd specify ± (or separate lower/upper tolerances in some situations). Using decimal points to indicate uncertainty was not a thing I believe I did after high school. Does any actual professional use decimal places and not explicit ±?
Similarly, we calculated those ± values using the chain rule/uncertainty propagation, not with the simple decimal place rules you learn as a kid. I assume no one serious uses the child rules when CAD software can just as easily use the real ones.
> we'd specify ± (or separate lower/upper tolerances in some situations)
> we calculated those ± values using the chain rule/uncertainty propagation
Yes, that's common in detailed engineering documents. It still doesn't change the fact if I ask for 3.000 and you give me 3.001 I'm not going to consider that in-spec despite not giving a ±. It's assumed if I wrote it out to that decimal point I'm caring about that level of precision.
> Using decimal points to indicate uncertainty was not a thing I believe I did after high school
Well, I'd imagine since the topic of lesson was understanding whole numbers at a basic level this was probably a high school or lower class, probably more like elementary or middle school. You know, in that time when you did use decimal places to indicate precision. This person wasn't talking about losing points at their engineering job.