Random-Number Seed
 
 
The seed of the random number generator can be set as follows: 
 
flag   Random:setSeed   
 (default = off)
Indicates whether a user-set seed should be used every time the 
Pythia::init routine is called. If off, the random number 
generator is initialized with its default seed at the beginning 
of the run, and never again. If on, each new Pythia::init 
call (should several be made in the same run) results in the random 
number being re-initialized, thereby possibly starting over with the 
same sequence, if you do not watch out. 
   
 
mode   Random:seed   
 (default = -1; maximum = 900000000)
The seed to be used, if setSeed is on.
 
A negative value gives the default seed,
 
a value 0 gives a random seed based on the time, and
 
a value between 1 and 900,000,000 a unique different random number 
sequence. 
   
 
 
For more on random numbers see here. 
This includes methods to save and restore the state of the generator, 
and some preprogrammed methods to generate non-uniform random numbers.