LATEX Equation Editor

In an earlier post I mentioned L^AT_EXiT, by Pierre Chatelier. The L^AT_EX Equation Editor is similar in function—and not entirely dissimilar in appearance.
I'm not sure yet which I prefer. Both are free—try both. If you already downloaded L^AT_EXiT last year, make sure you try the latest version.
If you have a Fink tetex installation, you must set the preferences for L^AT_EX Equation Editor to specify that L^AT_EX is in /sw/bin/ and ghostscript in /sw/share.
See also mimetex and L^AT_EX render.

ENTITY —(X)HTML entities in XML for XSLT

You can use character entities in your XML provided you declare them.

Add a DOCTYPE to your XML — all you need is the name of your root tag (my document in the example below is a recipe) and a reference to the special character sets you want.

for example

XML-compatible ISO Special Character Entity Set for XHTML

— including lt gt mdash quot euro

<?xml version="1.0" encoding="utf-8" standalone="yes"?> <!DOCTYPE recipe [        <!ENTITY % xhtml-special            PUBLIC "-//W3C//ENTITIES Special for XHTML//EN"        "http://www.w3.org/MarkUp/DTD/xhtml-special.ent" >        %xhtml-special; ]> <recipe>   ... </recipe> 

other standard character sets

You can add more declarations to the DOCTYPE mdash just add them between the square brackets [...]

XML-compatible ISO Latin 1 Character Entity Set for XHTML

— fractions, accented characters, pound, yen, cent, copy

        <!ENTITY % xhtml-lat1            PUBLIC "-//W3C//ENTITIES Latin 1 for XHTML//EN"        "http://www.w3.org/MarkUp/DTD/xhtml-lat1.ent" >        %xhtml-lat1; 

ISO Math, Greek and Symbolic Character Entity Set for XHTML

        <!ENTITY % xhtml-symbol            PUBLIC "-//W3C//ENTITIES Symbols for XHTML//EN"        "http://www.w3.org/MarkUp/DTD/xhtml-symbol.ent" >        %xhtml-symbol; 

LATEX iT

 \pi^2 =&6\sum_{i=0}^{\infty}\frac{1}{i^2}\\
\pi^4 =&90\sum_{j=0}^{\infty}\frac{1}{j^4}\\
\pi^6 =&960\sum_{k=0}^{\infty}\frac{1}{k^6} 

This small app from Pierre Chatelier allows you to create JPG and PDF images for inclusion in your web pages, easily from L^AT_EX math. Here you see a jpg — click the image to see the pdf.

When you generate a pdf file, L^AT_EX iT embeds the L^AT_EX source in the pdf, so that,later, you can paste the pdf back into this application, and edit the source. Brilliant!