## Mathematical text

### Inline LaTeX

Inline mathematical text is written in the normal way, enclosed by dollar signs: $…​$. For currency in regular text, use \\$.

Examples
subscripts

`＄a_1, \ldots, a_n＄` ⇒ $a_1, \ldots, a_n$.

superscripts

`＄x^2 + y^2 = z^2 ＄` = $x^2 + y^2 = z^2$

Greek symbols

`＄\alpha, \beta, ... \Omega＄` ⇒ $\alpha, \beta, ... \Omega$

Special symbols

＄\int_0^1 x^n dx＄ ⇒ $\int_0^1 x^n dx$,
＄\lim_{x \to 0} \frac{ \sin(x)}{x}＄ ⇒ $\lim_{x \to 0} \frac{ \sin(x)}{x}$
＄A \cap ( B \cup C)＄ ⇒ $A \cap ( B \cup C)$
Etc. See this list.

Grouping

`＄10^{-23} ＄` ⇒ $10^{-23}$

### Displayed LaTeX

For displayed formulas you may use double dollar signs, but it is better to use a pair of braces:

`                    $...$`
Examples
Matrices

$A = \left[ \begin{array} 11 & 2 \\ 3 & 4 \\ \end{array} \right]$ The matrix is rendered from the text

``` $A = \left[ \begin{array} 11 & 2 \\ 3 & 4 \\ \end{array} \right]$```
Partial differential equations

$- \frac{\hbar^2}{2m} \frac{\partial^2 \psi}{\partial x^2} + V\psi = i\hbar \frac{\partial \psi}{\partial t}$

The source text is

``` $-\frac{\hbar^2}{2m} \frac{\partial^2 \psi}{\partial x^2} + V\psi = i\hbar \frac{\partial \psi}{\partial t}$```

### Environments

Environments in Asciidoc-LaTeX work much like LaTeX environments, but have a different syntax and are more general. There are the typical mathematical environments (theorem, definition, equation, etc.), but also environments for chemical formulas and reactions as well as code listings. Here is a typical use for mathematics:

```[env.theorem]
--
A line is the shortest path between two points.
--```

It renders as

Theorem 1.
A line is the shortest path between two points.

You may label an environment for cross referencing, as in this example:

```[env.definition#def-point]
--
A point is that which has no breadth
--```

It renders as

Definition 1.
A point is that which has no breadth

The text after the hash mark is the label, or identifier.

To make the cross reference, enclose the label in double pointy brackets with no space:

```"The professor harrumphed haughtily:
I refer you to <<def-point>>."```

renders as

"The professor, harrumphed haughtily: I refer you to Definition 1."

Note that the the text "Definition 1" is a link.

Environments can contain LaTeX, as in the next example:

Theorem 2.
Let $f(x)$ be a continuous function. Then $\frac{d}{dx} \int_0^x f(u) du = f(x).$

### Special environments

There are a number of special environments whose content is processed differently from `env.theorem`, `env.definition`, etc.

Equation environment

It is generally better to use `env.equation` for displayed equations: if you want them to be numbered for later reference, just add an identifier. Here is an example without an identifier:

 $x^2 + y^2 = z^2$
```[env.equation]
--
x^2 + y^2 = z^2
--```

And here is an equation with an identifier:

 $x^d + y^d = z^d$ (1)
```[env.equation#fermat]
--
x^d + y^d = z^d
--```

Note that putting an identifier (`#fermat`) "turns on" the automatic numbering.

Equation align environment

One often needs to write aligned sets of equations, like these:

 $\begin{split} (a + b)^2 &= a^2 + 2ab + b^2 \\ (a + b)^3 &= a^3 + 3a^2b + 3ab^2 + b^3 \end{split}$ (2)

Here is the source code:

```[env.equationalign#binomials]
--
(a + b)^2  &= a^2 + 2ab + b^2 \\
(a + b)^3  &= a^3 + 3a^2b + 3ab^2 + b^3
--```

### Macros

You can use your own macros in a Scripta document. There are two ways to do this. The first is to add macros to the section you are working on like this:

```[env.texmacro]
--
\def\QQ{\mathbb{Q}}
\def\ZZ{\mathbb{Z}}
\newcommand{\set}[1]{ \{\,#1\,  \} }
\newcommand{\sett}[2]{ \{\,#1\, \mid\, #2\, \} }
--```
$\def\QQ{\mathbb{Q}} \def\ZZ{\mathbb{Z}} \newcommand{\set}[1]{ \{\,#1\, \} } \newcommand{\sett}[2]{ \{\,#1\, \mid\, #2\, \} }$

Then, if you write using the source code

``` $\QQ = \sett{ a/b }{ a, b \in \ZZ, b \ne 0}$```

the rendered text will be $\QQ = \sett{ a/b }{ a, b \in \ZZ, b \ne 0}$

Document-wide tex macros

The `env.texmacros` hack is quick and dirty, but has the disadvantage that the macros only work in the section in which they live. A better solution is to put all of your macro definitions in a special document, the `texmacros` document. To set up the `texmacros` document, proceed as follows: