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No, what is weird is that the original author seems to think you can look at a number and know how many significant digits it has. This is almost completely wr
by Trombone12 6y ago
No, what is weird is that the original author seems to think you can look at a number and know how many significant digits it has.
This is almost completely wrong: the number of significant digits is something given by metadata, you cannot look at a number and know that it has been properly rounded to the correct number of significant digits. You always need to be told this special circumstance because most numbers you encounter have in fact not been properly rounded.
- jhallenworld 6y agoIn the world of general chemistry, the significant figures rule is assumed. It's not a great rule because in this case: .000300 you have 3 significant figures. But in this case: 300000 you could have 1 to 6 significant figures. The convention to deal with this is always to use scientific notation: 3.00x10^5 has three significant figures.
- alisonkisk 6y agoIt's assumed that you shouldn't write down insignificant digits.
- Trombone12 6y agoNot sure how you're supposed to do floating point math while following that rule... you'll have better luck with writing C code with all semicolons in place.
- taeric 6y agoYou lost me on this one. :( There is the odd case of trailing zeroes in non decimal numbers, but otherwise if a number is written, when is that not assumed to be significant? That is, there are fairly standard rules for conveying significant digits, I thought?
- Trombone12 6y agoWhenever you've not personally done the error propagation and rounding yourself you shouldn't assume someone else has done it for you, and you should check if they have before trusting it. For example, the number you are viewing could have been produced with finite precision floating point math and then just rounded to an arbitrary chosen (small) number of digits.
- taeric 6y agoI mean... I don't disagree with this statement. But there are norms on how you are supposed to write numbers with significant digits.
- Trombone12 6y agoSure, but there is no typographical convention for how to indicate that a number is following such a norm so you can never tell from the number alone.