vLaTeX - Math parsing with LaTeX
 

vLaTeX allows your users to include mathematical equations written in LaTeX into their posts, rendered in high quality graphic files (either png or gif). Such ability is instrumental in scientific or educational oriented forums. When I started in vb two years ago, there ware a number of solutions available, but none of them suited my needs completely, so I developed my own integration between (a modified version of) Benjamin Zeiss' LatexRender and vBulletin. With the new vBulletin 4.0, I decided to improve some of the features of this product, and to release it with the hope that it turns out to be useful to any of you.


What is LaTeX?

LaTeX is a set of macros for the TeX typesetting system. It is the defacto standard of communication within the scientific and mathematical community. It works pretty much like a programing language: you write a text source file, and the latex executable compiles it in a DeVice Independent file (DVI), which can be later converted to the desired format (postscript, pdf, etc.).

This mod (thanks to a modified version of the LatexRender class) does all this work in the background. It takes the formula code, inserts it in a source file, compiles it and converts the output in a high quality image file (png or gif, depends on your settings) to show in the post.


Requirements

This mod relies on your server having available the following external programs. They are pretty standard in most Linux distributions, so hosts can install them easily (if they want to, some don't). Please, check your server meets this requirements (or ask your host to install the programs) before trying to use vLaTeX:

- latex: the LaTeX compiler. Check the TeX live distribution (http://www.tug.org/texlive/).

- dvips: converts the DVI file to PS. Usually included in all latex distributions.

- convert: as it name suggests, converts between a large number of graphic files. Belongs to the ImageMagick package. Needs ghostscript.

- identify: among other things, measures the size of image files. Also belongs to ImageMagick

- Ghostscript: PostScript and PDF language interpreter and previewer. Is called by convert in order to handle ps files.


Features

Creates a new BBcode, usually [TEX] (thought the tag name is configurable via the admin cp), which contents are processed thought LaTeX to generate image files. There are four calling modes:

- [TEX]E= mc^2[/TEX] in-line mode. The image is included in the middle of the text, without line breaks. It tries to adjust the baseline of the formula by adjusting the vertical-align CSS property; the results aren't always perfect, but it does its best.

- [TEX=null]E = m c^2[/TEX] displayed mode: The formula is displayed (usually centered) between two paragraphs.

- [TEX=*]E = m c^2[/TEX] auto-numbering mode: The formula is displayed (usually centered), and numbered.
NOTE: The auto-numbering depends on the CSS counter system, so some old browsers (most notably ie 7 and older) will show these equations untagged, like [TEX=null]. Don't blame me, blame non-standard compilant browsers.

- [TEX=tag]E = m c^2[/TEX] displayed with tag: The formula is displayed (usually centered) between two paragraphs, and tagged with the specific tag.

In the last two modes, the tags are displayed at the right (left if you use RTL) between brackets, in a (configurable) color.

The formulas are compiled by creating a small tex file and running the native LaTeX program throughout it. You can choose to wrap the formula with the standard dollar ($ ... $), the align or gather amsTeX environments. The standard dollar is recommended since the baseline hack works better with it, but the gather environment allows to create multiline equations using the \\ separator.

This mod also introduces a second BBcode, [EQREF]tag[/EQREF], which outputs (tag), with the same style of the equation tags. It's useful to let users make reference their formulas.

A double click on the image of a generated image will open a pop-up displaying the LaTeX source code used to generate the formula.

Menu with Common used LaTeX commands can be shown below the advanced mode editor. The admin can customize the commands of the menu thought the admin control panel.


Admin features

Image files are cached, so every unique formula is only processed once.

Fully configurable via Style Variables and templates. It is also fully phrased.

It doesn't change any vb default template, so upgrading should be easy.

Includes a list of blacklisted latex commands for security (configurable in the admin cp).

The admin can customize the preamble of the latex file in the admin cp. This is useful to define new commands that your community uses often, or to include packages.

Error messages can be customized in the phrase system.

Memory usage of ImageMagick commands (convert and identify) can be limited in the admin control panel.


Installation / Upgrade

1.- Unzip the mod files.

2.- Upload the vLaTeX directory to your forum root. The generated folder structure should look like this:

vLaTeX/
vLaTeX/index.htm
vLaTeX/class_vlatex.php
vLaTeX/functions_vlatex.php
vLaTeX/vlatex.js
vLaTeX/pics/
vLaTeX/pics/index.htm
vLaTeX/temp/
vLaTeX/temp/index.htm

3.- Change the permissions of the pics and temp folders so the web server can write on them.

4.- Import the product XML in your admin control panel. If you're upgrading, set "Allow Overwrite" to yes.

5.- Go to Admin CP > Settings > Options > vLaTeX - Math Parsing

6.- Make sure the path to latex, dvips, convert and identify executables is correct. Those settings default to the most common values in most linux distributions, but every host is a different world.
If you have shell access, you can check the location of the executables with the following commands:
which latex
which dvips
which convert
which identify

7.- Make sure the path to the Images and Temporal directory are correct. You can change them if you don't like the default value, but the directories must exist and the server must have permissions to write on them.
For extra safety, you could move the temp folder out of the public accessible directory three, thought it should not be needed, since files are deleted in matter of milliseconds.

8.- Set the rest of options as you wish.

9.- Test the product in some posts.

10.- If you wish to add a button in the advanced editor tool-bar for this mod, you can add it using the admin cp section Custom BB Codes (write anything you want in Replacement, this mod will overwrite it). You can use any tex icon, for instance http://www.iconfinder.com/icondetails/3780/16/tex_icon


Error messages

The LaTeX parsing can fail for a number of reasons. In such case, an error message is displayed instead of the formula. Here's a list of all possible error messages and their meaning:

- "Image too big {1}, max {2}x{3}", The resulting image is bigger than the allowed dimensions.

- "Blacklisted command", The user attempted to compile a formula with a forbidden command.

- "Can't move image", Image formula could be created, but I could not be moved to the destination folder. Check that the directory exists and has write permissions.

- "Convert failed", Formula could be compiled, but could not be converted to png/gif. Check the convert program path.

- "Compile failed", The formula could not be compiled. Check that the temporal directory has write permissions and that the latex path is correct.

- "Code too long, max. {1} characters", The formula code was too long. The maximum length can be configured in the admincp.

- "Formula not found", The compilation and convert process appeared to not raise any error, but the image was not found on the destination folder. Check for permissions in the destination folder and/or IO errors.

- "Pictures directory unwritable", The destination folder does not exist, or has no write permissions.

- "Temp. dir unwritable", The temporal folder does not exist, or has no write permissions.

- "Unknown error", Any other error condition.


Disclaimer

This mod is in beta phase, if you find bugs, please tell me how to reproduce them so I can improve it. It is distributed as is, with the hope that it is useful for someone, but without any warranty. Nor will I accept any responsibility or liability if it doesn't work as expected, or even if it breaks something.
This mod is mainly developed for personal usage. I will listen to good ideas, but I can't guaranty that I will be implemented requested features.


License

This mod is distributed under the LGPL.(http://www.gnu.org/copyleft/lesser.html). As is, you can freely distribute it or any derivative work provided that: 1) you acknowledge the work of the previous coders (like myself and Zeiss), 2) you release it under the same license (or GPL).



Acknowledgments

This mod (in particular, the class_vlatex.php file) is strongly based on the LatexRender class by Benjamin Zeiss (http://www.mayer.dial.pipex.com/tex.htm).

The baseline hack by the work of Maarten Sneep (http://mactextoolbox.sourceforge.net.../baseline.html).


Compatibility

The last version of this mod (0.5.1) requires vb4.2.0 or higher. It should work on previous CKEditor versions, but it was not tested.

If you wish to use it in a pre-CKEditor vb installation, you can use the previous vLaTeX version (0.4.1). If you want to use it in an older vb4.0.x release, you can download version 0.3 (which is compatible with vb4.0.1 or higher). Take into account that old versions of this hack have less features and might have some issues fixed in later versions.

Support will be given only for the last version of this mod.



History

2009 / 12 / 19 - First (beta) release

2009 / 12 / 20 - version 0.2
Fixed baseline problem of in-line formulas in CMS articles.
Improved error handling.
Included Spanish translation

2010 / 1 / 24 - version 0.3 (requires vb4.0.1)
Fixed extra space after in-line equations.
Won't break down if vb's CSS is stored as files.
New pop-up showing the formula source code upon double-click.

2010 / 7 / 23 - version 0.4 (requires vb4.0.4)
Improved support for CSS stored as files.
Fixed bug of js file not being loaded on certain servers.
Menu with common LaTeX commands under vb's advanced editors.
Equations will no longer be break by preview in blogs or CMS articles.

2010 / 4 / 24 - version 0.4.1 (requires vb4.0.4)
Improved compatibility of the Common Commands quick-menu with IE browser.

2012 / 12 / 07 - version 0.5.1 (requires vb4.2.0)
CKEditor support.
Memory limit for imagemagick commands.
Code pop-up now can overflow postbit boundary.

2012 / 12 / 17 - version 0.5.2 (requires vb4.2.0)
Introduced Formula Wrapper option.

Awesome! Tagged for use, after I upgrade to vb4.

Very neat. Tagges for later use.

Looks very promising! Planning to install it once my board goes life. Thanks for your work!

Don't have any need for this on our forums but I use latex day-to-day at work and just wanted to say this looks great. If anyone does run a forum with scientific/mathematical content then could come in really useful.

Since presumably vb4 will be released tomorrow, I have released version 0.2 fixing a minor issue with formulas in the CMS (it defines a margin to images which makes the baseline hack useless, unless removed by the mod's CSS).

I took the opportunity to add some more error handling (trying to prevent php errors when directories have the wrong permissions, for instance), and to include Spanish translation (sorry, don't know more languages myself :p).

very nice
thanks,

Man, I wish I had a reason to install this.

Thank you so much

*supertagged*

Love this mod, now I just need to install Gold when I get the time...

Have you looked into this library? http://www.math.union.edu/~dpvc/jsMath/

Yes I did. As I said, there's a number of options, each one with its pros and cons.

Updated with a new version (0.3) that fixes a few issues and adds a new feature: Users will be able to double-click a formula, and a pop-up will... well, pop. This pop-up displays the source code used to generate the image (of course, admin can choose to deactivate this new feature).

vLaTeX 0.3 requires vBulletin 4.0.1. I'll leave the 0.2 version available for download, since it works well with vBulletin 4.0.0 (and the RC versions).

I am getting this error on vB 3.6.7:
Fatal error: Class 'vB_Template' not found in /home/user/public_html/domain/forum/vlatex/functions_vlatex.php on line 39

Any ideas? Thanks

Architecture changes in vB4 makes this mod (as most) not backwards compatible with vB3.

The core functionality can be used without much difficulty in any version (as it depends on external programs such as latex, dvips and convert), but the bridge between it and vB (i.e, the way to handle templates) is completely different on vB4.

Ah, alright.

Edit: Solved: this works great

Any plans for an update on this mod?

What kind of update do you mean? It already works with latest vb version (I run it on vb 4.0.3 without any issue).

If you mean update for new features, then yes. But I can't tell you when it'll release or what new will include. It will be definitively after 4.0.4 (which doesn't mean that it will come out soon after 4.0.4).

Hi there,

Thanks for this great mod!

its working but the double click for code doesnt work... any ideas?
http://www.mathhelpforum.com/math-he...tml#post527732

Your bburl variable doesn't contain a trailing /, so the javascript file cannot be found. In the next release (which I don't know when will it be, but hopefully not long after 4.0.4), I'll add a check to add it manually.

In the while, so you can use the mod, please do the following. In your admincp, go to "Plugins & Products" > "Plugin manager" > "Product : vLaTeX" > "Include JS and CSS files". There, find the line

It should be the 5th line in the text area. Change it to:

Note that the only difference is a new / before vlatex/vlatex.js

Hope that helps.

Other than that, I see some permissions errors in your page, did you set the temp and pics folder to be writable by the webserver?

Thanks
I got a white page when I write [TEX=tag]E = m c^2[/TEX] and try to preview the thred !

You don't appear as having installed it.

Anyway, I'd need more info to troubleshot your problem, a link to your site or something.

Awesome! Thank you.

thanks alot, extremely useful .

installed and nominated.

This isnt working yet again.
Could you help?

I see the call to the javascript file has completely disapeared from your site. I really can't know why without "looking inside".

It'd help to know what happened between the moment it was working and now. Did you install some other mod? Changed the style?

On top of my head, a couple ideas you could try. If you installed a new style, make sure the headinclude template includes the line

If you installed a new mod, it might be "eating" the template hook. If so, it might help to change the execution order of the same plug-in you edited the last time (instead of 5, make it 100 or some other number bigger than any other mod).

Bills PayPal Donate Lite 4.0 (https://vborg.vbsupport.ru/showthread.php?t=236380)
was the problem.
When I disabled that product the source code came back up.

I would like to run both together. Any ideas?

I'd have to take a deeper into that mod and see why interacts with vlatex to find out what causes the problem. But I won't be able to do so until next Wednesday, I'll be out of town, I'm very sorry.

In the while, you can try to contact Bills, see if he can help you. Or you can try to paste the code directly into the headinclude template

I LOVE THIS PLUGIN!!! There isn't a simpler way of getting LaTeX working out there. It is quite simply amazing.

I just started using it and would love to add a couple buttons to the editor for the most common expressions I use. I am working with a group of Chemistry and Math teachers that would probably prefer not to have to learn latex for the simple things like subscript, superscript, fractions...

Can someone point me in the right direction for where I might be able to add some in?

I'd like to add something like that into the mod by default, but I'm not sure when I'll be able to get into that. If everything goes right, it could be this month.

First of all sorry for my bad english.
Since the version 4.05 I get shown on the CMS site following error:

In the forum everything works great.
What can be or where it goes wrong


Gr??e aus Germany :)

Please, click install to get support!

I'll take a look into that. Do you have the forums in a subdirectory of the CMS, or something like that?

In the like directory !
The error was not in 4.04 Version of vbulletin

Ps:
I have click install this great Mod :)

Sorry, but I cannot reproduce that problem in my vb405 test installation. Would you let me see your site? (send the link in pm if you don't want to do so publicly).

Hallo

The error occurs only in CMS, but not always
Here is a screenshot and the address of the Forum
Would be great if you could find the error

Greetings from Germany

http://www.hausaufgaben-forum.net/content/

Thanks for the image and the link.

I believe that the problem is caused because your widget called "Neuste Beitr?ge" (whatever that means :p) is trying to preview a post that contains a formula, the preview is stripped to a number of characters, so the code it contains becomes invalid LaTeX, causing the error. That's why it only happens in the CMS, it is the only part of vb that previews portions of posts.

As a temporary fix, please try this (untested, but should work): create a file called ".cache" (without the quotes, note there's a point in the beginning) and upload it to http://www.hausaufgaben-forum.net/vlatex/pics/.cache

This won't prevent the latex error in the widget, but at least should get rid of the php error in your header.

I've already started to work in the next release (that will at least include a quick-menu with common latex commands below the editor, among other things). I'll try to include a permanent fix for this problem in this new version.

This does not work with the tip. The error is to continue to see.
I'd be happy, that would see the error no longer in the CMS
Did you have another idea?

Open ./vlatex/functions_vlatex.php. Around the line 57 find

Replace it with

Next release of the mod will include this fix (among other things).

Runs perfect now
Thank you for your help :)

A teaser of the menu with common used commands that will be available with the next version of this mod (to be released in a few days).

Of course, you (the admin) can customize the commands displayed.