A trick for the pbs scripts on usc high performance computing cluster (HPC)

I'm trying to run LDA for different numbers of topics. I wrote a
bunch of m-files with all different number of topics hard coded but
then I realized it was being dumb. Actually, it might have saved time
this time, but in the long run I wanted to figure out the hpc pbs
scripts work. Basically its possible to pass variables from the shell
into the pbs script (you can't use the standard ENV vars b/c the job
is forked to different machines). The good idea I had was to pass the
qsub script the command I want to run (distribute) in the variable
CMD. This takes the responsibility out of the pbs script and puts it
back into a normal shell command, which I think is easier for my
purpos. All that's in the run.pbs script is:

#!/bin/bash

source source /usr/usc/matlab/default/setup.sh     #puts matlab on path
cd /auto/rcf-proj3/sn/kazemzad/machineLearningTest #goes to the dir that I want


echo $CMD             #assumes $CMD is passed using the -v switch
$CMD;                 #runs #CMD

(END)

Here's an example of how to use it for a test matlab script:

qsub -v CMD="matlab -nosplash -nodesktop -r \"2+2,exit\"" run.pbs

Here's an example of trying to put it all together for a number of topics

for x in 10 50 100 200 300 400 500 600 700 800 900 1000; do echo $x; qsub -l walltime=23:59:59,nodes=1:ppn=2 -v CMD="matlab -nosplash -nodesktop -r \"numTopicsExperiment($x),exit\"" run.pbs; done

This just forks all the different experiments with $x as a parameter.
These commands take 7+ hours to run, so I'm not actually sure it
works. At least it hasn't barfed yet. If I don't post back, assume
it worked and try it yourself if it suits your needs.