Primed variables with subscript horizontal subcript spacing

Question

Is there a way to make the prime symbol of the variable align horizontally with the subscript?

If I do $R\prime_0$ the 0 is too far from the R, I want it to be the same distance as if I do $R_0$. If I try to put the prime as a superscript, the prime symbol is too small.

Thanks!

Answer 1

The "prime" character was designed (by DEK) in TeX very special. The input symbol ' is set as math-active and it is defined by plain TeX (and in other formats too) like ^\prime (roughly speaking). Because superscript uses smaller font, the base prime character (printed directly by \prime) is designed somewhat bigger and it is never used in normal situations. The optimal size is only in superscript.

Why do you use complicated $R\prime_0$ instead of simple $R'_0$?

TeXbook says at page 130:

The control sequence \prime stands for the symbol (printed here), which is used mostly in superscripts. In fact this symbol is so big as it stands that you would never want to use it except in subscript or superscript, where it occurs in a smaller size.

Since single and double primes occur rather frequently, plain TeX provides a convenient abbreviation: You can simply type ' instead ^\prime and '' instead ^{\prime\prime}, and so on.

Answer 2

I suppose you want to write either R^{\prime}_0 (alias: R'_0) or R^{\textstyle\prime}_0. The latter looks ghastly, though, doesn't it?

\documentclass{article}
\begin{document}
$R^{\prime}_0 \quad  R'_0\quad R^{\textstyle\prime}_0$
\end{document}