#+TITLE:     How to circumvent ncf limitation of MathToWeb with Plastex?
#+AUTHOR:    Jambunathan K
#+EMAIL:     kjambunathan@gmail.com
#+DATE:      2011-11-01 Tue
#+DESCRIPTION:
#+KEYWORDS:
#+LANGUAGE:  en
#+OPTIONS:   H:3 num:t toc:t \n:nil @:t ::t |:t ^:t -:t f:t *:t <:t 
#+OPTIONS:   TeX:t LaTeX:t skip:nil d:nil todo:t pri:nil tags:not-in-toc

#+EXPORT_SELECT_TAGS: export
#+EXPORT_EXCLUDE_TAGS: noexport
#+LINK_UP:   
#+LINK_HOME: 
#+XSLT:

#+LATEX_HEADER: \usepackage{jambu}


* Summary

  This document outlines ways to circumvent limitations of "-ncf"
  option in MathToWeb. See this [[http://lists.gnu.org/archive/html/emacs-orgmode/2011-11/msg00017.html][discussion thread]] for understanding of
  the limitations.

* Settings
  
  Leave the converter command at it's default value - which doesn't
  use =-ncf= option.

#+begin_src emacs-lisp
  (setq org-latex-to-mathml-convert-command 
        "java -jar %j -unicode -force -df %o %I ")
#+end_src

* mysttyle.tex

  In the definitions below, one =newcommand= uses one another
  =newcommand=. The below defintions goes in to user specified stlyes
  file =mystyle.tex=.

#+begin_src tex
  \newcommand{\pressure}{p}
  \newcommand{\capillaryPressure}{\pressure_{c}}
#+end_src

* LaTeX Equation
  The latex equation below relies on above newcommand definitions to
  be available.

#+begin_src org
  ,#+LABEL: Equation:cp
  ,\begin{equation}
  ,\capillaryPressure=0
  ,\end{equation}
#+end_src

#+LABEL: Equation:cp
     \begin{equation}
     \capillaryPressure=0
     \end{equation}

* Flatten equations with Plastex

  Use [[http://wiki.lyx.org/LaTeX/ExpandNewcommands][plastex]] to flatten out the above equation. 

  The snippet below is a variation of script in the afore-mentioned
  link and takes input from stdin and spews out flattened equation to
  stdout.

  Copy the below script to =fixup.py=.

#+srcname: fixup.py
#+begin_src python
#!/usr/bin/python
# _*_ coding: UTF-8 _*_
import sys
from plasTeX.TeX import TeX
doc = TeX(file=sys.stdin).parse()
# The processed document is contained in the string doc.source
# Print to file
# f = open('PlastexProcessed.tex', 'w')
sys.stdout.write(doc.source.encode('utf-8'))
# f.close()
#+end_src

* Hack Org with a defadvice

  "sneak-in" custom processing in to org core by installing the advice
  below.

#+begin_src emacs-lisp
  (defadvice org-format-latex-as-mathml 
    (before my-org-format-latex-as-mathml activate)
    "Prepend mystyle.tex to latex-frag.
  Pass it through to \"plastex\". Use the flattened equation - which has
  ZERO DEPENDENCIES on user's newcommand definitions - as input to MathToWeb."
    (ad-set-arg 0 (and (ad-get-arg 0)
                       (with-temp-buffer
                         (insert-file-contents  "mystyle.tex")
                         (goto-char (point-max))
                         (newline)  
                         (insert (ad-get-arg 0))
                         (shell-command-on-region
                          (point-min) (point-max)
                          "./fixup.py" nil t 
                          (get-buffer-create "*plastex-errors*"))
                         (buffer-string)))))
#+end_src

* Export

  Export this file to ODT and see that above LaTeX equation is
  satisfactorily converted to MathML by MathToWeb.

* Disabling above advice

  You can disable the above advice anytime by doing this.

#+begin_src emacs-lisp
  (ad-disable-advice 'org-format-latex-as-mathml 'before
                     'my-org-format-latex-as-mathml)
  (ad-update 'org-format-latex-as-mathml)
#+end_src