As described in the eimsim
documentation, the functionality of package eimsim
is divided into things that need to be done only once and things which must be done 
times for simulation runs. The `done once' things can be further divided into those things which must be done before the simulation runs, and those things which must be done afterward. The `before' things are gathered into eimsimprep; the ` simulation runs' things are to be found within eimsimbatch; and the `afterward' things are performed within the present task eimsimreduce.
The task eimsimreduce does 4 things in sequence, which are described individually in the following four subsections.
each of the input source-list columns X, Y and FLUX: makes a frequency histogram of relative 
offset.