Steps to run the code:
0. Parepare the data sets. You can download ``a9a,'' ``real-sim,'' ``rcv1,''
   and ``news20'' from LIBSVM's data set page. For ``yahoojp'' and ``yahookr,''
   they are not publicly avaliable.
1. Lunch MATLAB command line
   > matlab
2. Compile rs.c
   >> make
3. Execute the experiment code.
   >> run