# Seth Woolley's Man Viewer

## Manual for random - man random

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```RANDOM(3)                  Linux Programmer's Manual                 RANDOM(3)

NAME
random(3,4,6), srandom, initstate, setstate - random(3,4,6) number generator

SYNOPSIS
#include <stdlib.h>

long int random(3,4,6)(void);
void srandom(unsigned int seed);
char *initstate(unsigned int seed, char *state, size_t n);
char *setstate(char *state);

DESCRIPTION
The random(3,4,6)() function uses a non-linear additive feedback random(3,4,6) number
generator employing a default table of size 31 long integers to  return
successive  pseudo-random numbers in(1,8) the range from 0 to RAND_MAX.  The
period of this random(3,4,6) number generator  is  very  large,  approximately
16*((2**31)-1).

The srandom() function sets its argument as the seed for a new sequence
of pseudo-random integers to be returned by random(3,4,6)().  These  sequences
are  repeatable  by  calling srandom() with the same seed value.  If no
seed value is provided, the random(3,4,6)() function is  automatically  seeded
with a value of 1.

The  initstate()  function allows a state array state to be initialized
for use by random(3,4,6)().  The size of the state array n is  used  by  init-
state() to decide how sophisticated a random(3,4,6) number generator it should
use -- the larger the state array, the better the random(3,4,6)  numbers  will
be.   seed is the seed for the initialization, which specifies a start-
ing point for the random(3,4,6) number sequence, and provides  for  restarting
at the same point.

The  setstate()  function  changes the state array used by the random(3,4,6)()
function.  The state array state is used for random(3,4,6)  number  generation
until  the  next  call  to initstate() or setstate().  state must first
have been initialized using initstate() or be the result of a  previous
call of setstate().

RETURN VALUE
The  random(3,4,6)()  function  returns  a  value between 0 and RAND_MAX.  The
srandom() function returns no value.  The  initstate()  and  setstate()
functions  return  a  pointer  to  the previous state array, or NULL on
error.

ERRORS
EINVAL A state array of less(1,3) than 8 bytes was specified to initstate().

NOTES
Current  "optimal"  values for the size of the state array n are 8, 32,
64, 128, and 256 bytes; other amounts will be rounded down to the near-
est known amount.  Using less(1,3) than 8 bytes will cause an error.

CONFORMING TO
BSD 4.3