Bugs in TeX

Bugs in TeX

by Hugo Troch -
Number of replies: 7

I met TeX while working on an old 286 with 2 floppy's and i still use fragments of the old files i wrote in those days. And still faithfull after all these years....
Moodle is new to me, but what an excitement to see TeX-possibilities in Moodle.
I used it with my students (17 years) and after 1,5 hours of instruction and excercising, they make beautiful formula's (including matrices, integrals and so on) on there forums.
Here are some bugs I want to report:

1. It's impossible to use < or > symbols. Propably a conflict with the html-tags?
2. When you want to correct an array-environment, the double backslashes  (to separate multiple rows)  are replaced by single ones.
3. It's impossible to separate the input of a formula over multiple lines. That's a problem for novices to TeX while writing matrices, etc.

friendly yours

Hugo Troch
Belgium

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In reply to Hugo Troch

Re: Bugs in TeX

by Zbigniew Fiedorowicz -

First of all you must understand that mimeTeX which we use to typeset TeX expressions is not a full implementation of TeX.  You certainly would not want to use it to publish your mathematics Ph.D. thesis on the web.  Please visit the mimeTeX home page at http://www.forkosh.com/mimetex.html for some idea about what it can or can not do.

As to inequalities, I don't see any problem in typing them within HTML Editor. Enter $$$x<2$$$ to get $$x<2$$ and $$$x>2$$$ to get $$x>2$$.  If you are entering inequalities without HTML Editor or in source mode within HTML Editor, you have to encode them like this &lt; for < and &gt; for >.

As to arrays, double backslashes, and multiline inputs and so on, you need to enter them in source mode within HTML Editor.  Otherwise HTML Editor inserts unwanted html tags like <p> and </p> inside the TeX expression. Here's an example of an array entered in source mode:

$$A=\(\array{3,c.cccBCCC$ &1&2&3\\\hdash~1&a_{11}&a_{12}&a_{13}\\ 2&a_{21}&a_{22}&a_{23}\\ 3&a_{31}&a_{32}&a_{33}}\)$$

I had some discussion with Janne about making HTML Editor more compatible with math. expressions here: http://moodle.org/mod/forum/discuss.php?d=4921
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In reply to Zbigniew Fiedorowicz

Re: Bugs in TeX

by Hugo Troch -

Quite right about inequalities.

But i have still problems while correcting expressions like:

$$\left|\begin{array}{cc}2&3\\4&5\end{array}\right| = 2.5 - 3.4$$

you lose one backslash every time you edit the formula.
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In reply to Hugo Troch

Re: Bugs in TeX

by Zbigniew Fiedorowicz -

Unfortunately, due to compatibility problems with HTML Editor mentioned in my previous post, editting complicated TeX expressions within this Editor is quite inconvenient.  Currently it is best to use some more TeX friendly editor to perfect the TeX, and then copy and paste the finished product in source mode into HTML Editor. Janne is working on improving this situation, but probably not in time for the Moodle 1.2 release.

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In reply to Hugo Troch

Re: Bugs in TeX

by David Scotson -
I have encountered a similar problem and think it is neither a TeX, mimeTex or HTMLeditor problem since I wasn't using any of them when I encountered it.

I was trying to backslash escape a backslash using the Markdown format i.e. enter \\ . It worked as expected until I tried to edit whereupon double backslashes were replaced with single ones.

Could it be something to do with the code for storing or retrieving strings from the database? Some brief testing suggests that the bug doesn't occur in the Forums but does in the resources.


(I didn't realise this thread was a year old when I posted, has anything happened in the last year?)
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In reply to David Scotson

Re: Bugs in TeX

by José Robles -

I don´t have that problem in these configurations:

a) Apache/1.3.28 mod_php4 + MySql 3.23.49 + Moodle 1.4.3 (2004083131)
b) Apache/1.3.31 (Unix) PHP/5.0.3 mod_perl/1.25 + MySql 3.23.58 + Moodle 1.4.3 (2004083131)
c) Apache/1.3.31 (Unix) PHP/5.0.3 mod_perl/1.25 + MySql 4.0.21 + Moodle 1.4.5 (2004083150)

 The double backslashes doesn´t (\\) were replaced with the re-edition of the resource/activity.  It´s work.

But, i have the problem with:
d) Apache/2.0.54 (Unix) PHP/5.0.4 + MySql 4.0.21 + Moodle 1.5.2 (2005060222)
e) Apache/2.0.54 (Unix) mod_ssl/2.0.54 OpenSSL/0.9.7g PHP/5.0.4  + MySql 4.0.21 + Moodle 1.5.2 (2005060222)

I think something to do with Apache 2 or Moodle 1.5. I going to update to moodle 1.5.2 one system with apache 1.3.x.

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