## WeBWorK Problems

### \xrightarrow

by Eric Stroyan -
Number of replies: 9
I've not had any luck figuring out how to get something using \xrightarrow to work. I did have this functioning on a previous installation, but I can't find my notes on what I did and I'm increasingly lazy at this time of year. This would be used something like \xrightarrow[MnO_{2}]{\Delta} in a chemical reaction to indicate catalysts or other added items such as heat. Davide's contextReaction.pl is brilliant for adding such items to the reaction scheme, but having such items under/over the reaction arrow is preferred in some instances. Any guidance would be most appreciated.

### Re: \xrightarrow

by Michael Gage -
You can get \xrightarrow to display if you use images display mode but not if you use jsMath or MathJax. For jsMath this command simply has not been implemented. It's possible that the amsmath tex headers are not being included in rendering using MathJax which would account for the problem there -- or it may be they just don't yet have glyphs for everything.

### Re: \xrightarrow

by Eric Stroyan -
Actually, I have the default view at images. I suspect I am not loading all the requisite fonts. If I recall \xrightarrow is part of the AMS font set or the 'additional' fonts. I could install chemarr or chemarrow, but I forget what I did to get those to work in WeBWorK in the past.

### Re: \xrightarrow

by Davide Cervone -
Both MathJax and jsMath implement \xrightarrow. For MathJax it is in the AMSmath extension, and for jsMath I think it was in MoreArrows or something like that. But you are right, you need to load the extension in order to have access to it.

Davide

### Re: \xrightarrow

by Eric Stroyan -

### Re: \xrightarrow

by Davide Cervone -
You should not need to load the fonts, as they will be loaded automatically by the AMSsymbols extension, as I recall. If you do load the fonts, be sure you do it as
    loadFonts: ["msam10","msbm10"]

with quotation marks and no "and". I assume you did, but wanted to be sure, since it wasn't what you typed. Note that this will only affect the jsMath output, not the image output that you have on my default, nor the MathJax output. Davide

### Re: \xrightarrow

by Eric Stroyan -
No I didn't have the 'and in the load (just my dullard-like copy and paste.) I'll check again exactly what I've set up. I suspect I've missed something rather simple. I suspect I've buggered something with the font installation elsewhere.
By the way that contextReaction.pl is brilliant. The students hate the predicting products problems. such reaction is usually a clear indication of success;)!

### Re: \xrightarrow

by Eric Stroyan -
I reinstalled some fonts and seems to have taken care of the issues I was having with TeX documents. This DID NOT fix what was going on in WeBWorK, but I tracked down what was going on...........
I'm stupid. Note to self...check to see that the correct version of a macro file containing symbols you will be using is, in fact, the one you will be using, not something else. I was actually not using something I thought I was, if you know what I mean. As Gilda Radner used to say "Oh, never mind."

### Re: \xrightarrow

by Davide Cervone -
We've all done the same thing. No harm done.

[I once spent an hour trying to debug a problem with a communications program (the ancient Kermit program) between a 128K mac and an Amiga 1000. Everything seemed to be working from the Amiga to the Mac, but nothing I typed on the Mac was making it back. I recompiled, checked the cables, and did everything else I could think of. Nothing. Then I noticed that the keyboard wasn't plugged into the Mac! Red-faced, I plugged it in and everything worked fine. I can hardly believe the I was able to do all the work for more than an hour on the Mac with just the mouse, and not the keyboard, but that's how it was.]

Davide