Using MathJax in R's help system

Hi,

?I am doing a small experiment to test if I can use

?MathJax ( official site: http://www.mathjax.org )

?in R's html help pages ?(i.e. options(help_type='html'))

?and it seems working with some minor modifications.


?The screenshot (rendered by Firefox 4.0 beta and with STIX fonts) of

?the help page in html format with MathJax enabled is at the following

?url:

?http://picasaweb.google.com/gongyi.liao/RDevel#5568989227748103346

?(the corresponding R.css in this srceenshot is obtained from

? Yihui Xie
http://yihui.name/en/2011/01/customizing-the-theme-of-your-r-html-help/ )

?I made a simple modification on

?R-2.12.1/src/library/tools/R/Rd2HTML.R

?with diff:

?435c435
< ? ? ? ? ? ? ? ? ? ?of1('$')
---

? ? ? ? ? ? ? ? ? ?of1("<i>")

439c439
< ? ? ? ? ? ? ? ? ? ?of1('$')
---

? ? ? ? ? ? ? ? ? ?of1("</i>")

444c444
< ? ? ? ? ? ? ? ? ? ?of1('</p>\\[')
---

? ? ? ? ? ? ? ? ? ?of1('</p><p align="center"><i>')

447c447
< ? ? ? ? ? ? ? ? ? ?of1('\\]<p>')
---

? ? ? ? ? ? ? ? ? ?of1('</i></p><p>')

688,694c688
< ? ? ? ? of0('<script type="text/javascript"
src="http://mathjax.connectmv.com/MathJax.js">\n',
< ? ? ? ? ? ? 'MathJax.Hub.Config({\n',
< ? ? ? ? ? ? 'extensions: ["tex2jax.js"],\n',
< ? ? ? ? ? ? 'jax: ["input/TeX","output/HTML-CSS"],\n',
< ? ? ? ? ? ? 'tex2jax: {inlineMath: [["$","$"]]}\n',
< ? ? ? ? ? ? '});\n',
< ? ? ? ? ? ? '</script>\n')
---

and the modified R-2.12.1/src/library/base/man/svd.Rd:

for demonstration:


47,51c47,50
< ? \deqn{ \mathbf{X} = \mathbf{U D V}^\top,} where \eqn{\mathbf{U}} and
\eqn{\mathbf{V}} are
< ? orthogonal, \eqn{\mathbf{V}^\top} means \emph{V transposed}, and
< ? \eqn{\mathbf{D}} is a diagonal matrix with the singular
< ? values \eqn{D_{ii}}{D[i,i]}. ?Equivalently, \eqn{\mathbf{D} =
< ? \mathbf{U}^\top \mathbf{X V}},\deqn{1 = \int_{\mathbb R}\phi(z)dz}
---

? \deqn{ \bold{X = U D V'},} where \eqn{\bold{U}} and \eqn{\bold{V}}

are

? orthogonal, \eqn{\bold{V'}} means \emph{V transposed}, and
? \eqn{\bold{D}} is a diagonal matrix with the singular
? values \eqn{D_{ii}}{D[i,i]}. ?Equivalently, \eqn{\bold{D = U' X V}},

?My personal opinion is, html is a better format for showing R help

?documents, because modern browsers can process some complicated

?interactive contents, while text editors (emacs, vim, etc.) and PDF

?readers (Adobe reader, evince, xpdf, etc.) only have limited ability

?to process complicated contents like interactive animations.


?But, at this moment, R's html help pages do not show the

?mathematical materials (I mean, the formula) in a proper

?way. R's PDF and PS help pages provide good mathematical

?material layouts but PDF and PS are better choices for printing

?rather than screen displaying.


?So, if R provides some mechanism that we can customize the

?html header in R's html help pages, like include some

?javascripts, then we could have much more flexible, accessible

?R help documents in html format and both users and developers

?can benefit from better reading experience.


?Any comments are greatly appreciated.






--
Gong-Yi Liao

Department of Statistics
University of Connecticut
215 Glenbrook Road ?U4120
Storrs, CT 06269-4120

860-486-9478