4.2BSD/usr/man/man3/rand.3c

.TH RAND 3C "19 January 1983"
.SH NAME
rand, srand \- random number generator
.SH SYNOPSIS
.nf
.B srand(seed)
.B int seed;
.PP
.B rand()
.fi
.SH DESCRIPTION
.ft B
The newer random(3) should be used in new applications;
rand remains for compatibilty.
.ft R
.PP
.I Rand
uses a multiplicative congruential
random number generator
with period 2\u\s732\s0\d
to return successive pseudo-random
numbers in the range from 0 to 2\u\s731\s10\d\-1.
.PP
The generator is reinitialized by calling
.I srand
with 1 as argument.
It can be set to a random starting point by calling
.I srand
with whatever you like as argument.
.SH "SEE ALSO"
random(3)