[u/mrichter/AliRoot.git] / PYTHIA8 / pythia8145 / htmldoc / RandomNumberSeed.html

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<title>Random-Number Seed</title>
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<h2>Random-Number Seed</h2>

The seed of the random number generator can be set as follows:

<p/><code>flag&nbsp; </code><strong> Random:setSeed &nbsp;</strong> 
 (<code>default = <strong>off</strong></code>)<br/>
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.
  

<p/><code>mode&nbsp; </code><strong> Random:seed &nbsp;</strong> 
 (<code>default = <strong>-1</strong></code>; <code>maximum = 900000000</code>)<br/>
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.
  

<p/>
For more on random numbers see <a href="RandomNumbers.html" target="page">here</a>.
This includes methods to save and restore the state of the generator,
and some preprogrammed methods to generate non-uniform random numbers.

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<!-- Copyright (C) 2010 Torbjorn Sjostrand -->
Commit	Line	Data
9419eeef	1	<html>
	2	<head>
	3	<title>Random-Number Seed</title>
	4	<link rel="stylesheet" type="text/css" href="pythia.css"/>
	5	<link rel="shortcut icon" href="pythia32.gif"/>
	6	</head>
	7	<body>
	8
	9	<h2>Random-Number Seed</h2>
	10
	11	The seed of the random number generator can be set as follows:
	12
	13	<p/><code>flag  </code><strong> Random:setSeed  </strong>
	14	(<code>default = <strong>off</strong></code>)<br/>
	15	Indicates whether a user-set seed should be used every time the
	16	<code>Pythia::init</code> routine is called. If off, the random number
	17	generator is initialized with its default seed at the beginning
	18	of the run, and never again. If on, each new <code>Pythia::init</code>
	19	call (should several be made in the same run) results in the random
	20	number being re-initialized, thereby possibly starting over with the
	21	same sequence, if you do not watch out.
	22
	23
	24	<p/><code>mode  </code><strong> Random:seed  </strong>
	25	(<code>default = <strong>-1</strong></code>; <code>maximum = 900000000</code>)<br/>
	26	The seed to be used, if <code>setSeed</code> is on.<br/>
	27	A negative value gives the default seed,<br/>
	28	a value 0 gives a random seed based on the time, and<br/>
	29	a value between 1 and 900,000,000 a unique different random number
	30	sequence.
	31
	32
	33	<p/>
	34	For more on random numbers see <a href="RandomNumbers.html" target="page">here</a>.
	35	This includes methods to save and restore the state of the generator,
	36	and some preprogrammed methods to generate non-uniform random numbers.
	37
	38	</body>
	39	</html>
	40
	41	<!-- Copyright (C) 2010 Torbjorn Sjostrand -->