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Although the two outputs look quite similar, what is the advantage of using $f^\prime$ instead of $f'$? By the way, here is my code:

\[‎ ‎f^‎\prime ‎(x)=y‎ ‎\]‎
\[‎ ‎f'‎ ‎(x)=y‎ ‎\]‎‎
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There's no advantage in using $f^\prime$; it's just more awkward to type than $f'$ and the result is exactly the same. – egreg Dec 15 '12 at 17:14
up vote 59 down vote accepted

' is defined in latex.ltx as active math character:

{\catcode`\'=\active \global\let'\active@math@prime}

The active ' looks for following ' and puts them together as superscript, a''' becomes a^{\prime\prime\prime}. Thus using ' makes the input easier to write.

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Sometimes you may want to pass LaTeX code as an argument to another program. In that case the code is typically wrapped in quotes. Using quote to mean a prime will confuse the second program. For example to type TeX in graphical output of MATLAB one may use something like


to print $F'$ at location $(0,0)$. Using $F'$ in the code however becomes problematic.

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use double quotes or escapes for the String? – MaxNoe Jan 26 '15 at 10:21
@MaxNoe Double quotes don't work in Matlab. String escaping is done with a double quote. So you'd have to write things like 'The symbol f'' is used to represent the first derivative of a function', which looks wrong at a first glance. All things considered, f^\prime doesn't look so bad. – Federico Poloni Feb 9 '15 at 22:18

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