You know what would be even cooler than @JosephWright's siunitx? One that you could write a value into, then flip a switch at the start of the paper, and it would print the value in those units. So when your prof tells you to redo everything in millimole instead of micromole you don't have to edit every value in the whole paper.
@DavidCarlisle If I ever write a computer virus it will be a very sneaky one that will sit in memory and convert all Imperial measurements to metric and refuse to let you change them back.
@egreg yes but if it's all just changing between different si prefixes so by some power of 10 it's probably not that hard to do accurately. Changing between metres per second squared and furlongs per square fortnight might be trickier.
@Canageek comes with practice; like you probably know, typography is an art, and (La)TeX is only one of it's best brushes; in art, all of practice, luck and talent count.
@yo' Chemist. My job is easier as whatever I do have a sample size of over 10^20, which makes life much easier ;)
@yo' But readability is a science, so you can eliminate all that messy opinion by finding whatever is the easiest to read. Then you establish that as the standard.
@Canageek that's a case where only the objective measures are important. But in typography, there's more into it. Note that you for instance choose font to suit the mood of the text. For instance, I like CM/LM for mathematical or engineering texts as the cut of the font is clear, very precise in some sense. I much more prefer e.g. Palatino for belletry and similar stuff, as the font has a nice touch of ... how to say ... it simply gives a warming feeling when you read text written in it.
@Canageek with the emphasis on as much as possible. It can't choose the font, it can't tell you how big the graphics have to be, it can't tell you how large the delimiters should be in this case to make the formula look nice.
@Canageek The single fraction in the middle could have \left and \right; but there's the exponent which would land too high and, most important, the outer brackets: if you use \bigg in the middle (which is what \left and \right would do), also the outer ones should be \bigg, but they'd leave too much white space around f.
@yo' Yes, but this is only relevant for mathematical formula, so you've got a built in set of circumstances. You know precision and comprehension are important. You know that it will be in scientific papers. You know that lack of ambiguity is the single most important consideration.
@egreg Right, but it sounds like a logic tree could handle all of this. Also, how much of that is preference and how much would influence reading comprehension?
@Canageek No, no and no. Now imagine you have a similar formula elsewhere in the paper that contains something which can't be enclosed in this size of delimiter. Now what do you prefer -- consistency between the formulae so that the reader at first glance considers them similar, or the technically most proper typesetting of each of the formulas separately?
(This is not the best example actually, but consider that you have to choose between \tfrac and \dfrac for each of them and for each of them separately, you would choose differently, but now you consider them being together, and you're stuck. You again have to decide how important is that they look similar.)
@Canageek With the due proportions, it happened to me the same as Knuth. I liked very much how my first published paper was printed. The second one went to the same typography, but they had bought a computer system instead of doing hand typesetting of math. The result was incredibly poor.
How do I move the underbrace out of the big parentheses while still keeping it underneath the term?
\begin{alignat*}{4}
& \frac{E_{0-0}}{hc} &&= C+\frac{E'(\upsilon'=0)}{hc} &\\
& &&= C+\frac{1}{hc}\left(\hbar\omega'_e\left(0+\frac{1}{2}\right)-\underbrace{\hbar\chi'\omega'_...
@yo' In which case, I'd probably set an algorithm that sets them each separately, assigns some parameters, finds the formula that would suffer from being typset wrong, then reset it with all of the formula using that set of parameters, or some compromise between them.
@yo' Right, you'd have to set up a case study, and sit a few hundred people down with eye trackers and a series of comprehension questions to know for sure.
@Canageek but the computer can't even check if the formulas are similar but completely irrelevant or not so similar but very relevant! Because the computer can't understand the paper contents as it's written in human language.
@egreg that's not the problem IMHO, it really only adds to the complexity. The problem is that formulas have a meaning, and the set of possible formulas is really infinite, whereas the set of words is moreorless finite.
@egreg yeah, I wasn't sure I prefer a tabular line over a big|, but it's probably better with teh tabular line. Also, this is exactly the case when I make the parentheses smaller...
@yo' That doesn't matter: Why would it? I want to show that these symbols are in these brackets, what is inside the brackets doesn't matter as long as I can clearly see what is in them, and clearly understand what is inside them.
@yo' Give me an example then. Way I see it, an integral is an integral and a superscript 2 is a superscript 2. Just make the sqrt and braces clear and you are good to go.
@Canageek sorry, I don't have time to bother. But if you want an example: I would possibly treat $A$ differently as an operator than as a number. I wouldn't like an operator $A$ to be in \tfrac for instance, with a number -- no problem.
@yo' I think you are taking this a lot further then I am. I just think there is an optimal placement of () that you should be able to infer from the formula, at least in the vast majority of cases.