14.13 @math: Inserting Mathematical Expressions

You can write a short mathematical expression with the @math command. Write the mathematical expression between braces, like this:

@math{(a + b)(a + b) = a^2 + 2ab + b^2}

This produces the following in Info and HTML:

(a + b)(a + b) = a^2 + 2ab + b^2

The @math command has no special effect on the Info and HTML output. makeinfo expands any @-commands as usual, but it does not try to produce good mathematical formatting in any way.

However, as far as the TeX output is concerned, plain TeX mathematical commands are allowed in @math, starting with ‘\’, and the plain TeX math characters like ‘^’ and ‘_’ are also recognized. In essence, @math drops you into plain TeX math mode.

This allows you to conveniently write superscripts and subscripts (as in the above example), and also to use all the plain TeX math control sequences for symbols, functions, and so on, and thus get proper formatting in the TeX output, at least.

It's best to use ‘\’ instead of ‘@’ for any such mathematical commands; otherwise, makeinfo will complain. On the other hand, input with matching (but unescaped) braces, such as ‘k_{75}’, is allowed inside @math, although makeinfo would complain about the bare braces in regular input.

Here's an example:

@math{\sin 2\pi \equiv \cos 3\pi}

which looks like the input in Info and HTML:

\sin 2\pi \equiv \cos 3\pi

Since ‘\’ is an escape character inside @math, you can use @\ to get a literal backslash (\\ will work in TeX, but you'd get the literal ‘\\’ in Info). @\ is not defined outside of @math, since a ‘\’ ordinarily produces a literal ‘\’.

For displayed equations, you must at present use TeX directly (see section Raw Formatter Commands).