[LON-CAPA-users] Forcing students to submit valid expressions for formula responses.

[Stuart Raeburn]

Hi,

> Or can someone finds similarities of the hosts 'mtal1' and 'scll1'
> that may cause this bug :-/  ?

Yes, that is a good observation.

Both mtal1 and scl1 are running a Linux distro for which the distro's  
standard repos provide maxima rev. 5.23

The majority of other LON-CAPA servers in the production cluster use  
distros for which the maxima version is 5.20.

In the case of a syntax error, maxima 5.23 outputs "incorrect syntax"  
instead of "Incorrect syntax" as it did in previous versions.

The result of this change in case is that LON-CAPA's lonmaxima daemon  
rev. 1.40 included with LON-CAPA 2.10.1, and earlier, will not respond  
with a "BAD_FORMULA" response (which causes display of: "Unable to  
understand formula" as feedback to the student), but instead will  
timeout with (a much less helpful) display of: "An internal error  
occurred while processing your answer. Please try again later."

Anyway LON-CAPA servers with Linux distros with maxima 5.23 and later  
(i.e., CentOS/Scientific Linux/RHEL 6, SLES 10/11, Fedora 14 and  
later, SuSE 11.1 and later) should have someone with root access to  
the server update /home/httpd/perl/lonmaxima to rev. 1.41 as follows:

wget -O /home/httpd/perl/lonmaxima  
'http://source.loncapa.org/cgi-bin/cvsweb.cgi/~checkout~/loncom/lonmaxima?rev=1.41;content-type=text%2Fplain'

/etc/init.d/loncontrol restart

As restarting the LON-CAPA daemons impacts users, this action should  
be scheduled for a time of limited user activity.

Note: lonmaxima rev. 1.42 (which also includes the fix for bug 6653 to  
address occurrences of "code ran too long" a different origin -- this  
time seen only sporadically, and also on Linux distros besides  
CentOS/Scientific Linux/RHEL 6 -- which Justin had remarked on in an  
earlier post in this thread is included in the forthcoming LON-CAPA  
2.11.0.


Stuart Raeburn
LON-CAPA Academic Consortium


Quoting Peter Dencker <dencker at math.uni-luebeck.de>:

>
> Hi,
>
> you wrote
>
>> Right now my LON-CAPA server times out on them,
>> and asks them to try again later.
>
> I've tested it: You seem to suffer by the same strange maxima-bug
> on host 'mtal1', see the 'catching maxima errors'-threads on
> http://mail.lon-capa.org/pipermail/lon-capa-users/2012-November
>
> The problem is still unsolved.
> Therefore you have to check *all* syntax errors.
> This was the initial motivation for my library-project.
>
> Maybe I can offer a preliminary workaround-library ...
>
> Or can someone finds similarities of the hosts 'mtal1' and 'scll1'
> that may cause this bug :-/  ?
>
> - Peter
>
>
> Am 21.10.2013 16:23, schrieb Angus Findlay:
>> When I give students formula response questions some of them don't   
>> submit valid mathematic expressions. The most common problems are:
>>
>> 1) Not having balanced brackets. (i.e. number of left brackets do   
>> not match number of right brackets)
>> 2) Including invalid characters, such as quotation signs.
>> 3) Not including brackets, when necessary. (eg. 2^-1/2 instead of 2^(-1/2))
>>
>> I want to tell them that the expression is invalid, tell them why,   
>> and allow them to enter it again, without penalty. (Right now my   
>> LON-CAPA server times out on them, and asks them to try again later.)
>>
>> Is there a piece of standard code I can use for this, or if not,   
>> what it the easiest to implement a solution to this?
>>
>> Thanks in advance.
>>
>> Respectfully,
>> ----------------------------------------------
>> Mr. Angus Findlay
>> Math Department, Mount Allison University
>> Sackville, New Brunswick
>>
>> email: afindlay at mta.ca    tel: 506-364-2592
>> ----------------------------------------------
>>
>>
>>
>>
>> _______________________________________________
>> LON-CAPA-users mailing list
>> LON-CAPA-users at mail.lon-capa.org
>> http://mail.lon-capa.org/mailman/listinfo/lon-capa-users
>>
>
>
> --
> Dr. Peter Dencker
>     wissenschaftl. Mitarbeiter
>
> UNIVERSITÄT ZU LÜBECK
>     INSTITUT FÜR MATHEMATIK
>
>     Ratzeburger Allee 160
>     23562 Lübeck
>
>     Tel +49 451 500 4254
>     Fax +49 451 500 3373
>     dencker at math.uni-luebeck.de
>
>     www.math.uni-luebeck.de
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