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Command: rand | Section: 3 | Source: UNIX v10 | File: rand.3
RAND(3) Library Functions Manual RAND(3)
NAME
rand, lrand, frand, nrand, srand - random number generator
SYNOPSIS
int rand()
long lrand()
double frand()
int nrand(val)
int val;
srand(seed)
int seed;
DESCRIPTION
Rand uses a linear feedback random number generator to return uniform
pseudo-random numbers x, 0<=x<2^15, with period about 2^32.
Lrand returns a uniform long x, 0<=x<2^31, with period about 2^48.
Frand returns a uniform double x, 0.0<=x<1.0, always a multiple of
2^-31.
Nrand returns a uniform integer x, 0<=x<val.
The generators are initialized by calling srand with whatever you like
as argument. To get a different starting value each time,
srand((int)time((long *)0));
will work as long as it is not called more often than once per second.
BUGS
Rand and lrand are quite machine-dependent. Although frand and nrand
are more portable, they appear in few versions of Unix.
RAND(3)