[LON-CAPA-users] Algebra Expression Rendering in LON-CAPA

Harding, Gene L glhardin at purdue.edu
Fri Jan 13 23:41:10 EST 2017

Hi Damien,

Thanks for your reply. At least now I know that I was chasing the wind. I was able to get close by using Sigma in place of sum in the expression, but then only the "n" was subscripted, not the "=1" part, even though I used braces: _{n=1}...

I had initially tried to render the equation in the xml portion of the problem, but when I did that I had a lot of trouble properly displaying some of the variables using the <m>$...$</m> command. It worked in some places but not others.

This is as close as I have been able to get to a proper expression:

[cid:image001.png at 01D26DF0.DF719FF0]

In the xml portion I have been able to render it nicely:

[cid:image002.png at 01D26DF6.82F21010]

...but only if I hard-code the constants in the two fractions and inside the sine. Is there a way to display variable values from the perl script in place of the constants? I have tried a few things, but all were unsuccessful.


Gene L. Harding, PE

Associate Professor of ECET


Purdue University-South Bend

-----Original Message-----
From: lon-capa-users-bounces at mail.lon-capa.org [mailto:lon-capa-users-bounces at mail.lon-capa.org] On Behalf Of Damien Guillaume
Sent: Friday, January 13, 2017 10:17 PM
To: Discussion list for LON-CAPA users <lon-capa-users at mail.lon-capa.org>
Subject: Re: [LON-CAPA-users] Algebra Expression Rendering in LON-CAPA

> This is the call from the xml to render it:


> <center> <algebra>$function</algebra></center>

The algebra element has its own syntax. I do not know if it is documented, but we can look at the code at


The regular expressions used to recognized functions are:

my $trigfname = '(?:(?:a(?:rc)?)?(?:sin|cos|tan|sec|csc|cot)h?)';

my $otherfunc =


There is no sum. To display a sum, you could use the TeX syntax as Gerd suggested, within <m>$ $</m>.



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