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mathML versus LaTeXRender

No math
today. If you’re interested in the latest on noncommutative geometry,
head over to the NCG-blog where Alain Connes has a post on
Still, Alain’s post is a good illustration of what Ill be rambling about
TeX and how to use it in a blog.

If you’re running a math-blog,
sooner or later you want to say something more than new-age speak like
‘points talking to each other’ and get to the essence of it. In short,
you want to talk math and it’s a regrettable fact that math doesnt go
well with ASCII. In everyday life we found a way around this : we all
use TeX to write papers and even email-wise (among mathematicians) we
write plain TeX-commands as this language is more common to us than
English. But, plain TeX and the blogosphere don’t mix well. If you’re
expecting only professional mathematicians to read what you write, you
might as well arXiv your thoughts. Im convinced the majority of people
coming here (for whatever reason) dont speak plain-TeX. Fortunately,
there is technology to display TeX-symbols on a blog. Personally, I was
an early adapter to
LaTeXRender and even today a
fair share of page-views relates to the few
posts I did on
how to get latexrender working on a mac. Some time ago I
switched to mathML and now I’m
regretting I ever did…

Mind you, I’m convinced that mathML is the
‘proper’ way to get TeX to the internet but there are at the moment some
serious drawbacks. For starters, it is highly user-unfriendly. You
simply cannot expect people to switch browsers (as well as installing
extra fonts) just because they come to your site (or you have to be a
pretty arrogant git). Speaking for myself, Im still having (against my
better judgment) Safari as my default browser, so when I come to a site
like the n-category cafe I just
skim the plain-text in between and if (and only if) the topic interests
me tremendously I’ll allow myself to switch to Flock or Firefox to read
the post in detail. I’m convinced most of you have a similar
surfing-attitude. MathML also has serious consequences on the
server-side. If you want to serve mathML you have to emit headers which
expect everything to follow to be purified XHTML. If I ever forget a
closing tag in a post, this is enough to break down NeverEndingBooks to
all Firefox-users. I’ve been writing HTML since the times when the best
browser around was something called NCSA Mosaic so Ive a
pretty lax attitude to end-tags (especially in IMG-tags) and Im just
getting too old to change these bad habbits now… It seems I’m not the
only one. Many developers of WordPress-plugins write bad XHTML-code, so
the last couple of weeks I’ve been spending more time fixing up code
than writing posts. If you want to run a mathML-wordpress site you might
find the following hints helpfull. If you get a ‘yellow screen of
death’ when viewing your site with Firefox, chances are that one of your
plugin-authors missed a closing tag in the HTML-rendering of his/her
plugin. As a rule of thumb : go for the IMG-tags first! I’m sorry to
say, but Latexrender-Steve
is among the XHTML-offenders. (On a marginal note, LaTeXrender also has
its drawbacks : to mathematicians this may seem incredible but what
Latexrender does to get one expression displayed is to TeX an entire
file, get the image from the ps-file turn it into a gif and display it,
so one gets a GIF-folder of enrmous proportions. Hence, use Latexrender
only if you have your own server and dont have to care about memory
constraints. Another disadvantedge was that the GIFs were displayed with
a vertical offset, but this has been solved recently (use the ‘offset
beta’ files in the distribution)). Wrt. to that offset-beta version, use
this latex.php file instead (I
changed the IMG-line). Some plugins may not serve the correct headers
to display mathML. So, if you want to allow readers to have a
printer-friendly version of your mathML-post, get the WP-print plugin BUT
change to this wp-print.php file in order to
send the proper headers. Sometimes there are just forgotten lines/tags
in the code, such as in the [future calendar plugin](
plugin.html). So, please use this version
of the future.calendar.php file. And so on, and so on. The joys of
trying to maintain a mathML-based blog… So, no surprise I’m seriously
considering to ditch mathML and change to normal headers soon. One of
the things I like about LaTeXRender is that it can be extended, meaning
that you can get your own definitions and packages loaded whereas with
mathML you’re bound to write iTeX, which Ill never manage. But, again,
mathML will be the correct technology once all major browsers are mathML
capable and the font-problem is resolved. Does anyone know whether
Safari 3 (in Leopard, that is Mac OS 10.5 to the rest of you) will be

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Latexrender and dvonn boards

In order
to blog a bit about Dvonn-strategy, I made myself a simple Dvonn
LaTeX-template which works very well on paper but which gets mutilated
by Latexrender, for example the first situation of the looks

$~\xymatrix@=.3cm @!C @R=.7cm{ & & \Black{2} \connS & &
\bull{d}{5} \conn & & \bull{e}{5} \conn & & \bull{f}{5} \conn & &
\bull{g}{5} \conn & & \bull{h}{5} \conn & & \SWhite \connS & & \SWhite
\connS & & \SWhite \conneS & & \\ & \bull{b}{4} \conn & & \SBlack
\connS & & \Black{6} \connS & & \bull{e}{4} \conn& & \bull{f}{4} \conn &
& \bull{g}{4} \conn & & \bull{h}{4} \conn & & \SWhite \connS & &
\SWhite \connS & & \SWhite \conneS & \\ \SBlack \connbeginS & &
\SBlack \connS & & \BDvonn{7} \connS & & \bull{d}{3} \conn & & \SBlack
\connS & & \BDvonn{6} \connS & & \bull{g}{3} \conn & & \bull{h}{3}
\conn & & \Dvonn \connS & & \SWhite \connS & & \SWhite \connendS \\ &
\Black{5} \connbeginS & & \bull{b}{2} \conn & & \SBlack \connS & &
\bull{d}{2} \conn & & \bull{e}{2} \conn & & \bull{f}{2} \conn & &
\bull{g}{2} \conn & & \bull{h}{2} \conn & & \SWhite \connS & & \SWhite
\connendS & \\ & & \bull{a}{1} \con & & \bull{b}{1} \con & & \Black{5}
\conS & & \bull{d}{1} \con & & \bull{e}{1} \con & & \bull{f}{1} \con & &
\bull{g}{1} \con & & \bull{h}{1} \con & & \White{2} & &} $

reason behind this unwanted clipping is that Latexrender uses
**convert** to take the relevant part of a ps-page containing only the
TeXed formula on an empty page by performing clipping and then converts
it into a GIF-file (or any other format you desire). The obvious way
round this is to enlarge my template by adding two additional rows and
columns and putting visible nonsense there (such as dots) to enlarge the
relevant part so that no clipping is done of essential info. But then
(1) the picture generated becomes even larger than that above and (2) I
don’t want you to see the extra nonsensical dots… The essential line
in the **class.latexrender.php** file is

$command =
$this->_convert_path." -density ".$this->_formula_density.
" -trim -transparent \"#FFFFFF\" ".$this->_tmp_filename.".ps ".

I needed to delve into the [manual pages for the convert command](
of the ImageMagick-package. To my surprise, the *-trim* option (which I
thought to adjust somewhat by adding parameters) doesn’t exist! Still, I
got around my second problem using the *crop* option and around the
first by using the very useful *geometry* option. The latter is also
useful if you find that the size of the output of Latexrender is not
compatible with the size of your regular text. Of course you can amend
this somewhat by using the *extarticle* documentclass (as suggested) but
if you want to further adjust it, use for example


to size the output to exactly 86% (or whatever you need).
So, whenever I want to do some Dvonn-blogging from now on I’ll change my
class.latexrender.php file as follows

$command =
$this->_convert_path." -crop 0x0-10% -crop 0x0+10% -density
".$this->_formula_density. " -geometry 80%
-transparent \"#FFFFFF\" ".$this->_tmp_filename.".ps ".

produces the output

$\xymatrix@=.3cm @R=.7cm{.& & & & & & & & & &
& & & \\ & & & \Black{2} \connS & & \bull{d}{5} \conn & & \bull{e}{5}
\conn & & \bull{f}{5} \conn & & \bull{g}{5} \conn & & \bull{h}{5} \conn
& & \SWhite \connS & & \SWhite \connS & & \SWhite \conneS & & & \\ & &
\bull{b}{4} \conn & & \SBlack \connS & & \Black{6} \connS & &
\bull{e}{4} \conn& & \bull{f}{4} \conn & & \bull{g}{4} \conn & &
\bull{h}{4} \conn & & \SWhite \connS & & \SWhite \connS & & \SWhite
\conneS & & \\ & \SBlack \connbeginS & & \SBlack \connS & &
\BDvonn{7} \connS & & \bull{d}{3} \conn & & \SBlack \connS & &
\BDvonn{6} \connS & & \bull{g}{3} \conn & & \bull{h}{3} \conn & &
\Dvonn \connS & & \SWhite \connS & & \SWhite \connendS & . \\ & &
\Black{5} \connbeginS & & \bull{b}{2} \conn & & \SBlack \connS & &
\bull{d}{2} \conn & & \bull{e}{2} \conn & & \bull{f}{2} \conn & &
\bull{g}{2} \conn & & \bull{h}{2} \conn & & \SWhite \connS & & \SWhite
\connendS & & \\ & & & \bull{a}{1} \con & & \bull{b}{1} \con & &
\Black{5} \conS & & \bull{d}{1} \con & & \bull{e}{1} \con & &
\bull{f}{1} \con & & \bull{g}{1} \con & & \bull{h}{1} \con & & \White{2}
& & & \\ . & & & & & & & & & & & & & } $

which (I hope) you will
find slightly better…

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latexrender plugin for wordpress under tiger

Promises and pie-crusts are made to be broken, a wiser man once
said. Still, promises have a much longer life-span and sometimes their
real content becomes redundant over time.

A year ago, I
to document how I got the
LaTeXRender Plugin for WordPress
working under OS X. The procedure
consisted of some trial-and-error operations, installing non-standard
versions of software and hardcoding certain directories throughout
certain files…

Not something I was looking forward
to when I decided to upgrade this WordPress blog but,
surprisingly, things went pretty smoothly this time (Mac-technology
has improved a lot). So, please don’t worry too much about this
and follow the (late) instructions below.

things first : I will assume you have the ‘generic’ LaTeX
running under Tiger (10.4),that is, use the i-Installer to download BOTH
LaTeX and Imagemagick! Further, in order to get WordPress up and
running, have the standard
MySQL 4.0 package
installed for 10.3 (not version
4.1…) and don’t use the generic Mac-PHP version, but
instead download Marc
Liyanage’s PHP5 package
which has plenty of additional
packages installed (notably, GDlib and MCRYPT which comes in handy if
you want to fight spam-comments using BotCheck).


Download wp-
and follow the instructions given to the letter
(there is one undocumented extra directory you have to fill in at the
start of the latexrender-plugin.php file). There is
just one additional thing to do. Find in the
class.latexrender.php file the line starting

// convert dvi file to postscript using

and include the following lines just before it

// begin of workaround // extending the PATH
  environmental variable Soldpath =
  getenv(“PATH”); Swhere_imagemagick_is =
  “/usr/local/bin”; if (Soldpath) { Swhere_imagemagick_is .=
  “:Soldpath”;} putenv(“PATH=Swhere_imagemagick_is”); //
  end of workaround 

activate the plugin and it
should work! Still, there are three things you may want to change. In
the latex.php file uncomment the indicated lines as
you will be using htmlArea to input your posts. In addition, if you
have the MarkDown-plugin enabled, it is best to append additional
lines such as

 Slatex_formula =
  str_replace(“_”,”_”,Slatex_formula);     Slatex_formula

between the first ” ” should be the beginning and end
em-tag respectively) or underscores will be interpreted as em-tags.
If you run into additional similar problems, the procedure is to
comment-out the line


near the end of class.latexrender.php , look in the
tmp directory for the TeX-file, detect the problem and add similar
lines to the ones above to solve it. Another useful thing to do
is to add TeX-packages in the class.latexrender.php file. My own
version has the following predefined symbols and loaded

 function wrap_formula(Slatex_formula) { 
  Sstring  =
  .”}\\n”;  Sstring .=
  “\\usepackage[latin1]{inputenc}\\n”;  Sstring .=
  “\\usepackage{amsmath}\\n”;  Sstring .=
  “\\usepackage{amsfonts}\\n”;  Sstring .=
  “\\usepackage{amssymb}\\n”;  Sstring .=
  “\\usepackage{xy}\\n”;  Sstring .=
  “\\xyoption{all}\\n”;  Sstring .=
  #1}}\\n”;  Sstring .= “\\\\newcommand{\\mathbb{C}c}{\\Bbbk}\\n”; 
  Sstring .= “\\\\newcommand{\\mathbb{C}}{\\mathbb{C}}\\n”;  Sstring .=
  “\\\\newcommand{\\mathbb{Q}}{\\mathbb{Q}}\\n”;  Sstring .=
  “\\\\newcommand{\\mathbb{Z}}{\\mathbb{Z}}\\n”;  Sstring .=
  “\\\\newcommand{\\mathbb{N}}{\\mathbb{N}}\\n”;  Sstring .=
  “\\\\newcommand{\\mathbf}[1]{{\\\\text{\\em \\usefont{OT1}{cmtt}{m}{n}
  #1}}}\\n”;  Sstring .= “\\pagestyle{empty}\\n”;  Sstring
  .= “\\begin{document}\\n”;  Sstring .=
  “S”.Slatex_formula.”S\\n”;  Sstring .=
  “\\end{document}\\n”;          return Sstring;     }  

which, among other things, allow all commenters to add
quiver-pictures using xymatrix and vtx to depict vertices. Oh yes, you
can allow comments to include LaTeX-code by uncommenting the

  // add_filter(‘comment_text’,

in the latexrender-plugin.php
file (but before you do make sure you have spam under control, such as
with BotCheck mentioned above). That’s all for now. If you want
to use TeX in a comment, make sure to put the code between tags [ tex
] and [ /tex ] (omitting the extra spaces). If you want me to add
other LaTeX-packages, leave a comment.

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