======Running your MATLAB script on IGRIDA=======
This tutorial details the procedure to launch a MATLAB script as an OAR job on IGRIDA. 

=====Limitations=====
Beware of the number of licences for MATLAB as each OAR job will consume a token. Prefer compiling your script as in the following [[compiled_matlab_on_igrida|tutorial]].

=====Logging In=====
Start by connecting the IGRIDA frontend using SSH:
<code bash>
mymachine%ssh mylogin@igrida-oar-frontend
</code>

Welcome to the IGRIDA frontend! It is prohibited to start processes at this level, only interactive or batch OAR jobs are allowed.

=====Preparing the Scripts=====
As a good practice, it is recommended that you create a log directory, located in ''/temp_dd/igrida-fs-1/mylogin'', where the run will take place. In particular, your run outputs should never be written to your home directory, which would necessarily drive to an NFS crash at some time. For instance, type:
<code bash>
igrida-oar-frontend%mkdir -p /temp_dd/igrida-fs1/mylogin/log/
</code>

Then, create an OAR launch script in your home directory ''/udd/mylogin/matlab-igrida-demo/''. In this script, you start by loading the Matlab module. You can also specify the number of cores and the wall time. Do not forget to redirect the output and the error of the OAR job. The launch script ends by calling your Matlab m-file.

<file bash oar-launch-script.sh>
#!/bin/bash
source /etc/profile.d/modules.sh
module load matlab

#OAR -l core=10,walltime=6:00:00
#OAR -O /temp_dd/igrida-fs1/mylogin/log/job.%jobid%.output
#OAR -E /temp_dd/igrida-fs1/mylogin/log/job.%jobid%.error
echo "My job was ran on these nodes:"
cat $OAR_NODEFILE

#Setup MCR cache directory locally
export MCR_CACHE_ROOT=/tmp/mcr_cache_${USER}_OAR_JOBID_${OAR_JOBID}
mkdir -p $MCR_CACHE_ROOT

#cd to your execution directory first
cd /udd/mylogin/matlab-igrida
matlab -r matlab-demo

#Remove temporary MCR cache directory
/bin/rm -rf $MCR_CACHE_ROOT
</file>

In your Matlab file ''matlab-demo.m'', all the output must be redirected to the ''/temp_dd/igrida-fs1/mylogin/'' filesystem. Here is a simple example:

<code bash>
a=1;
b=a+1;
matFilename = sprintf('/temp_dd/igrida-fs1/mylogin/results.mat');
save(matFilename,a,b);
</code>

Prepare you OAR launch script to be executed:
<code bash>
igrida-oar-frontend%chmod +x oar-launch-script.sh
</code>
=====Launching the Job=====
You can now submit the job using the command ''oarsub'' as in the following:
<code bash>
igrida-oar-frontend%oarsub -S  oar-launch-script.sh
[ADMISSION RULE] Modify resource description with type constraints
[ADMISSION RULE] Job walltime greater than 4 hours, adding property duration_weight > 2 (large job).
Generate a job key...
OAR_JOB_ID=666666
</code>
  
Step back and watch your job being executed. 

=====Verifying the Output=====
If you need to follow the execution of your job, you can check the status of all your jobs:
<code bash>
igrida-oar-frontend%oarstat -f | grep mylogin
</code>

and verify the output or the errors generated using a specific job ID:
<code bash>
igrida-oar-frontend%more /temp_dd/igrida-fs1/mylogin/log/job.jobID.output
igrida-oar-frontend%more /temp_dd/igrida-fs1/mylogin/log/job.jobID.error
</code>