## Hypertext Help with LaTeX

### Subscripts

To get an expression, exp, to appear as a subscript, you just type _{exp}.

Can be used only in math mode. Thus, for a simple expression that is part of the running text:


H$_2$O is the formula for water


should display as "H2O is the formula for water". Note that the braces around the argument may be omitted if the subscript is a single character.

If a symbol has both subscripts and superscripts, the order doesn't matter. The following are equivalent:

    a_n^2


and

    a^2_n


Subscripts are normally displayed in a smaller font; to prevent this and, for example, use a standard Roman font, one would use;

    $J_{\rm Roman}$