plan9 man page for rand

RAND(2) 							System Calls Manual							   RAND(2)

NAME
       rand, lrand, frand, nrand, lnrand, srand - random number generator

SYNOPSIS
       #include <u.h>
       #include <libc.h>

       int    rand(void)

       long   lrand(void)

       double frand(void)

       int    nrand(int val)

       long   lnrand(long val)

       void   srand(long seed)

DESCRIPTION
       Rand returns a uniform pseudo-random number x, 0<=x<215.

       Lrand returns a uniform long x, 0<=x<231.

       Frand  returns  a uniform double x, 0.0<=x<1.0, This function calls lrand twice to generate a number with as many as 62 significant bits of
       mantissa.

       Nrand returns a uniform integer x, 0<=x<val.  Lnrand is the same, but returns a long.

       The algorithm is additive feedback with:

	      x[n] = (x[n-273] + x[n-607]) mod 2^31

       giving a period of 2^30 x (2^607 - 1).

       The generators are initialized by calling srand with whatever you like as argument.  To get a different starting value each time,

	      srand(time(0))

       will work as long as it is not called more often than once per second.  Calling

	      srand(1)

       will initialize the generators to their starting state.

   Alef
       There is no rand in Alef.

SOURCE
       /sys/src/libc/port/rand.c

																	   RAND(2)