The qsort(3) routine is replaced by a more usual quicksort (taken from Handbook of Algorithms and Data Structures, http://www.thunderstone.com/jump/demos/algorithms/hbook.html). The performance problem disappered.
Note that this corresponds to the change of the version 1.0 to 1.1 of the program itself.
The main routine is rewrited to use commandline arguments instead of the parameter file.
No change in functionality. Just made some bug fix so that the code can be compiled with g++ 2.8.1. Previous versions works only with 2.7.2 or older.