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How to run on a local file
If you are running on lxplus, first cd to a directory with a lot of space
cd /tmp/<username>
Download an example AOD file from the Grid, and if running on simulated data, also download a conditions database file:
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To process all events in a recorded-data file, download a file:
dq2-get -f data10_7TeV.00159086.physics_MuonswBeam.merge.AOD.f275_m548._lb0002-lb0021.1 data10_7TeV.00159086.physics_MuonswBeam.merge.AOD.f275_m548
and run a command like this:
processAOD_trf.py AOD.pool.root data10_7TeV.00159086.physics_MuonswBeam.merge.AOD.f275_m548._lb0002-lb0021.1 False ntuple.root 0 NONE -1
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float fcn( void* var1, void* var2 ) {
float* f1 = (float*)var1;
float* f2 = (float*)var2;
/* return the product of these two floats */
return (*f1)*(*f2);
}
As you see, in doing this, the programmer assumes all responsibility for making sure that the types and operations
are correct, something normally (and best) done by the compiler.