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Note:These pages make extensive use of the latest XHTML and CSS Standards. They ought to look great in any standards-compliant modern browser. Unfortunately, they will probably look horrible in older browsers, like Netscape 4.x and IE 4.x. Moreover, many posts use MathML, which is, currently only supported in Mozilla. My best suggestion (and you will thank me when surfing an ever-increasing number of sites on the web which have been crafted to use the new standards) is to upgrade to the latest version of your browser. If that's not possible, consider moving to the Standards-compliant and open-source Mozilla browser.

May 29, 2006

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, a b c d.
pmatrix
a matrix, enclosed in parentheses, (a b c d).
bmatrix
a matrix, enclosed in square brackets, [a b c d].
Bmatrix
a matrix, enclosed in brace brackets, {a b c d}.
vmatrix
a matrix, enclosed in vertical bars, ∣a b c d∣.
Vmatrix
a matrix, enclosed in double vertical bars, ∥a b c d∥.
smallmatrix
a small matrix, suitable for use in inline equations, a b c d.
cases
cases construct, ∣x∣={x forx≥0 , −x forx<0 .
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 A= (a b c d) A −1 = 1 detA(d −b −c a) = 1 ad−bc(d −b −c a)

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=∑ m,n∈ℤ m≥na 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.

Update (5/31/2006):

Spurred by Urs’s question, I decided it was time to produce some new documentation for itex2MML. It’s not much, but check out the itex Command Summary Page.

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!).

Update (6/2/2006):

For yet more enhancements, see the next entry.

1 Getting \href to work in comments required a small rejiggering of our sanitize spec.

Posted by distler at 10:44 AM | Permalink | Followups (6)

May 27, 2006

AdS/Au-Au II

Previously, I wrote about AdS/CFT computations of the jet-quenching parameter. A related quantity is the energy loss of a heavy quark moving through the quark-gluon plasma. Herzog, Karch, Kovtun, Kozcaz and Yaffe have a beautiful recent paper treating this latter problem.

Continue reading “AdS/Au-Au II” ...
Posted by distler at 12:41 AM | Permalink | Followups (3)

May 26, 2006

Bug in Crypt::OpenPGP

Ben Trott probably has other, more high-flying things to think about than a bug in a (probably long-forgotten) Perl Module. But Austin Frank recently uncovered an obscure bug in Crypt::OpenPGP, which we use here to verify PGP-signed comments.

Most people, these days, have a DSA primary key (used for signing) and an El-Gamal subkey (used for encryption). Austin has an RSA primary key and DSA (signing) and El-Gamal (encryption) subkeys. Nothing wrong with that and, as far as I can tell, GnuPG handles such keys just fine. But Crypt::OpenPGP seems to barf on any message signed by Austin, leading me to suspect a bug in its handling of keys of this sort.

I’ve filed a bug report, but I’m not holding my breath.

Posted by distler at 9:25 AM | Permalink | Followups (5)

May 20, 2006

Techni