This should serve as a fast way to generate merger trees out of gadget snapshots.

We use the rockstar halo finder (http://code.google.com/p/rockstar/) and consistent-trees (http://code.google.com/p/consistent-trees/) by Peter Behroozi.

1) Building Rockstar:
Simply type make in the Rockstar directory

2) Building Consistent-Trees:
Using consistent_trees-0.96.1, typing make gives an error that the linking of
math.h went wrong. This can be fixed by adding -lm to OFLAGS in src/Makefile (already
corrected in this repo). Apart from that, make should work without problems.

2) Running Rockstar:
In the files rockstar-server.cfg and rockstar-client.cfg we have to specify the path
to our snapshot files (INBASE) and the directory, where the output should be saved. We
also have to provide a list with the filenames to be processed (snapshot_names.dat).
To do this, one one can use the provided prepare_rockstar.py and giving the snapshot directory
as argument, the *.cfg file are updated automatically, and also the snapshot_names is generated.
After this is done, we can start Rockstar through
./rockstar -c rockstar-server.cfg
./rockstar -c rockstar-client.cfg

3) Running Consistent-Trees
First we have to generate the DescScales.txt. To do this, execute
python extract_scales.py
Then we switch into the consistent_trees directory and start consistent_trees via the command
perl do_merger_tree.pl ../ctree.cfg

TODO:
- ask peter about importance of the h values which can be given to rockstar and consistent_trees

That's it :-)