Musings

itex2MML 1.1

One of the annoying misfeatures of itex2MML, heretofore, was that it used a rather nonstandard syntax,

\array{ ... } or
\array{ \arrayopts{...} ... }

to create matrices and aligned equations. I’m not sure of the historical origin of this peculiarly un-LaTeX-like syntax but, for some time now, I’ve been meaning to add support for the standard AMSLaTeX constructs.

With itex2MML 1.1, we now support

\begin{env}
   ...
\end{env}

where env is any one of the following

matrix

a matrix, $$\begin{matrix} a & b \\ c & d \end{matrix}\, .$$

pmatrix

a matrix, enclosed in parentheses, $$\begin{pmatrix} a & b \\ c & d \end{pmatrix}\, .$$

bmatrix

a matrix, enclosed in square brackets, $$\begin{bmatrix} a & b \\ c & d \end{bmatrix}\, .$$

Bmatrix

a matrix, enclosed in brace brackets, $$\begin{Bmatrix} a & b \\ c & d \end{Bmatrix}\, .$$

vmatrix

a matrix, enclosed in vertical bars, $$\begin{vmatrix} a & b \\ c & d \end{vmatrix}\, .$$

Vmatrix

a matrix, enclosed in double vertical bars, $$\begin{Vmatrix} a & b \\ c & d \end{Vmatrix}\, .$$

smallmatrix

a small matrix, suitable for use in inline equations, $\begin{smallmatrix} a & b \\ c & d \end{smallmatrix}$.

cases

cases construct, $$|x|=\begin{cases}x&\text{for}\, x\geq 0,\\ -x& \text{for}\, x\lt 0.\end{cases}$$

aligned

produces aligned equations (or sub-blocks thereof).

So

$$
\begin{aligned}
   A =& \begin{pmatrix}a & b \\ c & d \end{pmatrix} \\
   A^{-1} =& \frac{1}{\det A}  \begin{pmatrix}d & -b \\ -c & a \end{pmatrix} \\
     =& \frac{1}{a d - b c}  \begin{pmatrix}d & -b \\ -c & a \end{pmatrix}
\end{aligned}
$$

produces $$\begin{aligned} A =& \begin{pmatrix}a & b \\ c & d \end{pmatrix} \\ A^{-1} =& \frac{1}{\det A} \begin{pmatrix}d & -b \\ -c & a \end{pmatrix} \\ =& \frac{1}{a d - b c} \begin{pmatrix}d & -b \\ -c & a \end{pmatrix} \end{aligned}$$

Another AMSLaTeX construct I’ve been pining for is \substack{...}, as in

$$
   A = \sum_{\substack{m,n \in \mathbb{Z} \\ m \geq n }} a_{m,n}
$$

which now produces $$A = \sum_{\substack{m,n \in \mathbb{Z} \\ m \geq n }} a_{m,n}$$

If you’re viewing this in Mozilla/Firefox, you’ll note that the vertical spacing in all these matrices (and in \substack{...}) is screwed-up because of this bug.

For sheer lack of time, I don’t see myself implementing the myriad of other AMSLaTeX constructs anytime soon. But if there are particular ones you’ve been pining for, let me know.

As usual, my distribution comes with precompiled binaries for MacOSX and Linux and a plugin for MovableType.

In the process of reviewing the features of itex2MML, I made a slew of bugfixes/improvements. So it’s time to release itex2MML 1.1.2 with the following improvements.

• \backslash is now mapped correctly.
• \Box was added as a synonym for \square.
• Several characters were changed from <mo>s to <mi>s.
• Wide and regular-width accents now work as expected (well, except for this bug with \overline).
• Corrected support for \pmod and add support for \mod.
• Status-line messages in \toggle were a NOOP. Dropped.
• Fixed the \href command so that it will play nice with the W3C Validator, and hence will work here¹. If you downloaded itex2MML in the past few hours, download it again, to get the fixed-up version (sorry 'bout that!).