math-modesymbols
In math mode, writing \prime gives too big a "prime" symbol, and it isn't a superscript, like it always is in textbooks. Why is this?
This isn't a question about how to get \prime to be a superscript, I know that. The questions is about the reasoning behind why it isn't like that by default.
For many symbols it’s just that the purpose is different. Consider the set minus: what you want there isn’t a backslash. You really want a “set minus” – which just happens to be displayed (sometimes) identically to a backslash. But it’s still fundamentally different.
Now, which of the two LaTeX codes is more readable:
\mathcal{F} \backslash \{ 0 \}
% or
\mathcal{F} \setminus \{ 0 \}
If the two are really identical (which I don’t believe since as Carsten points out there’s always the issue of spacing in math mode) one can simply be defined in terms of the other – e.g.:
\newcommand*\setminus{\backslash}
No harm in that. This still makes the usage more readable (see above) and the macro can be exchanged very quickly if you decide that the symbol should be displayed differently. For example, consider that the set minus is actually often written like a normal minus instead of like a backslash. If you have used the \backslash command, you now need to change all occurrences of that in your document.
If you have used a dedicated command then you only need to redefine that:
\newcommand*\setminus{\ensuremath{{}-{}}}
In practice, I redefine aliases for almost all macros that I use to fit my current use-case.
The prime symbols are not too low, they're too small: you're requesting that first level sub/superscripts are 6pt, which is too small next to an 11pt size symbol.
Computing 80% of 11pt gives 8.8pt, and the standard first level sub/superscript size for 11pt is 8pt. Of course you need arbitrarily scalable fonts for this to work (\usepackage{lmodern}, for instance); just do the math:
\DeclareMathSizes{\@xipt}{\@xipt}{8.8}{7.7}
(but these values are too big, in my opinion and I'd leave the default). The font size used for subscripts is the same as the size used for superscripts and this can't be avoided. You can force big subscripts (typically uppercase letters) to be pushed a bit down by specifying a dummy superscript: compare
$a_{X} a^{}_{X}$
Best Answer
This is actually one of the exercises in The TeXBook
:)(exercise 16.5, p. 130):And the answer is: