RAND(2) RAND(2)
NAME
rand, lrand, frand, nrand, lnrand, srand - random number
generator
SYNOPSIS
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<2^15.
Lrand returns a uniform long x, 0<=x<2^31.
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 * (2^607 - 1).
The generators are initialized by calling srand with what-
ever 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.
Page 1 Plan 9 (printed 12/21/24)