<chapter name="Random-Number Seed"> 
 
<h2>Random-Number Seed</h2> 
 
The seed of the random number generator can be set as follows: 
 
<flag name="Random:setSeed" default="off"> 
Indicates whether a user-set seed should be used every time the 
<code>Pythia::init</code> 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 <code>Pythia::init</code> 
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. 
</flag> 
 
<modeopen name="Random:seed" default="-1" max="900000000"> 
The seed to be used, if <code>setSeed</code> is on.<br/> 
A negative value gives the default seed,<br/> 
a value 0 gives a random seed based on the time, and<br/> 
a value between 1 and 900,000,000 a unique different random number 
sequence. 
</modeopen> 
 
<p/> 
For more on random numbers see <aloc href="RandomNumbers">here</aloc>. 
This includes methods to save and restore the state of the generator, 
and some preprogrammed methods to generate non-uniform random numbers. 
 
</chapter> 
 
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