** Using WeBWorK **

I'm trying to display a matrix in a problem. This is the code for the matrix:

[ Q = begin{pmatrix} 1 & -2 \ 1 & 4 end{pmatrix}. ]

However, when viewing the problem, an image is of a lambda_1. There is a lamba_1 in another part of the same problem, and that one displays find.

If one of the entries in the matrix is changed, for example I've changed the 4 to a 45, then the matrix is displayed fine. If I change it back to 4 then the image just shows a lambda_1 again.

What can be done to fix this or stop it happening again?

Michal.

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Just as an experiment, try adding an extra space or two to the TeX expression, say

\[ Q = begin{ pmatrix} 1 & -2 1 & 4 end{pmatrix }. \]

and see if that works. The point is I want you to change the TeX input expression in a way thst does not change the TeX output.

Arnie

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Thanks for your relpy.

I've now tried putting a few spaces in, but it had no effect. I've replaced the pmatrix with a \left( , \matrix and \right) , so I now have the output I wanted. I may not be able to always to do this however.

Michal

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I would be interested in figuring out the problem, but there are a few things you could do to help.

First set the problem back to however it was when it produced the wrong image, and then remove all old images from the server so that it has to produce new ones. To remove cached images, as root:

  /opt/webwork2/bin/remove_stale_images --days=0 --delete

Once you have the file which produced the faulty image again, post it here (use pre tags to preserve it as much as possible). It may loose some backslashes, but I can figure out where they go.

John

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I don't have root access to the server. I will find out and ask if they can remove the old images.

Thanks,

Michal.

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