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`@math`

: Inserting Mathematical ExpressionsYou can write a short mathematical expression with the `@math`

command. Write the mathematical expression between braces, like this:

@math{(a + b) = (b + a)}

This produces the following in Info and HTML:

(a + b) = (b + a)

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 use produce good mathematical formatting in any way
(no use of MathML, etc.). The HTML output is enclosed by
`<em>...</em>`

, but nothing more.

However, as far as the TeX output is concerned, plain TeX
mathematical commands are allowed in `@math`

, starting with
‘`\`’. In essence, `@math`

switches into plain TeX math
mode. (Exception: the plain TeX command `\sup`

, which
typesets the mathematical operator name ‘sup’, must be accessed as
`\mathopsup`

, due to the conflict with Texinfo’s `@sup`

command.)

This allows you 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.

The `@sub`

and `@sup`

commands described in the previous
section produce subscripts and superscripts in HTML output as well as
TeX; the plain TeX characters `_`

and `^`

for
subscripts and superscripts are recognized by TeX inside
`@math`

, but do nothing special in HTML or other output formats.

It’s best to use ‘`\`’ instead of ‘`@`’ for any such
mathematical commands; otherwise, `makeinfo`

will complain.
On the other hand, `makeinfo`

does allow input with matching
(but unescaped) braces, such as ‘`k_{75}`’; it complains about
such 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 two characters ‘`\\`’ in Info).
`@\`

is not defined outside of `@math`

, since a ‘`\`’
ordinarily produces a literal (typewriter) ‘`\`’. You can also use
`@backslashchar{}`

in any mode to get a typewriter backslash.
See Inserting a Backslash.

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