2011/1/20 Gabriel Sandor <gabi.t.sandor(a)gmail.com>
So eventually I tried this and indeed it works as
expected. I have one more
question though.
I've seen that most of the complex math formulas are converted into .png
images with some long names - for instance, the <math>\iiiint\limits_F \,
dx\,dy\,dz\,dt</math> formula (triple integral) is converted into an image
with the name 49005f50f3ba2dfade3a265ebe363ee9.png. I'd like to know, is
this file name unique for each formula ? And is it persisted on the wiki's
server indefinitely, just like other images in articles ? To be more clear,
is the triple integral formula always going to be associated to this
49005f50f3ba2dfade3a265ebe363ee9.png
file ?
I'm trying to implement a cache mechanism in my app that tries to also deal
with images generated from math markup (besides usual images in articles),
that's why I have this curiosity. I'd like to know if I can safely associate
a math markup string with a file name so that there's no need to retrieve
the image from the server again when I encounter that formula.
On Mon, Dec 13, 2010 at 1:23 PM, Roan Kattouw <roan.kattouw(a)gmail.com>wrote;wrote:
2010/12/13 Gabriel Sandor
<gabi.t.sandor(a)gmail.com>om>:
Is it possible to retrieve (preferably via the
MediaWiki API) an image
representing a mathematical formula given in the <math> tags that are
frequently encountered in Wikipedia articles ?
There's no direct way to do
this, although I guess it could be
implemented. A workaround would be to do something like
http://en.wikipedia.org/w/api.php?action=parse&text=
<math>\gamma=\frac{1}{\sqrt{1-v^2}}</math>&format=yamlfm
, which will give you the HTML generated for this <math> tag, which
could be an image (like in this case), or HTML if the formula is
sufficiently simple (try a^2+b^2=c^2 for instance).
Roan Kattouw (Catrope)
Yes, the name is unique, I discovered by reverse engineering that it is
merely "the MD5 transformation of the normalized TeX code". An intelligent
trick that, I guess, points directly on the png image without any need to
calculate it again: I presume that the name only is calculated, and, if the
png exists, it is uploaded! The "normalized TeX code", I guess, is the text
that you can see browsing the html code, into the "alt" attribute of the
image tag.
There are online free MD5 coders somewhere into the web, try the conversion
of alternate text.
Nothing of this is documented, I discovered it by myself; can be, I'm
absolutely wrong. :-)
Alex