"500 2000 0.000001 3 3 1 1"

These numbers control the simplex downhill minimization algorithm's behavior. 500 specifies the first point of the simplex should have coordinates between -250 and 250. 2000 specifies the initial size of the simplex. 0.000001 is the convergence tolerance. The first 3 specifies that when computing landmark coordinates, the minimization should be performed 3 times and the best solution is chosen. The second 3 says that the minimization should be repeated 3 times when computing ordinary host coordinates. The next 1 says the simplex downhill algorithm should restart once to confirm convergence after each run. The final 1 specifies that random numbers from /dev/urandom should be used. If you are not running Linux, this might not be available, and you should set this parameter to 0 so rand() is used instead to generate random numbers. But then you will need to change gnp.c to specify a real random seed to srand() in main().

Except for the last parameter that controls the random number generation, you probably can leave the rest of the parameters as is.