Date: Sat, 28 Nov 1998 21:58:27 -0600 (CST) From: Chris Costello <chris@furrball.dyn.ml.org> To: bf20761@binghamton.edu, freebsd-hackers@FreeBSD.ORG Subject: Re: random number and primitive polynomial Message-ID: <199811290358.VAA01271@furrball.dyn.ml.org> In-Reply-To: <Pine.SOL.L3.93.981128221547.22947A-100000@bingsun2>
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> From chris Sat Nov 28 21:43:00 1998
> Date: Sat, 28 Nov 1998 22:21:56 -0500 (EST)
> From: zhihuizhang <bf20761@binghamton.edu>
> To: hackers <freebsd-hackers@FreeBSD.ORG>
> Subject: random number and primitive polynomial
>
>
> Hi, I am now interested in how a truly random number is generated. The
> source code is contained in file random_machdep.c. Can anyone tell me
> where I can find good reference on how the primitive polynomial is related
> to random number generation (i.e., its properties and role in a random
> number generator).
In /usr/src/lib/libc/stdlib/rand.c:
int
rand()
{
return ((next = next * 1103515245 + 12345) % ((u_long)RAND_MAX + 1));
}
In /usr/include/stdlib.h:
#define RAND_MAX 0x7fffffff
>
> By the way, I can not find where the file stdlib.h is located. According
> to the manual, rand() are defined in it. I want to look at the source
> code of rand() too (although it is said to be a bad random number
> generator).
/usr/include/stdlib.h
It only declares the function in the .h file. Try looking around
in /usr/src/lib/libc/stdlib for the stdlib function sources. (NOTE:
You must have installed the source distribution to see this.)
>
> Any help is appreciated.
>
> --------------------------------------------------
> | Zhihui Zhang, http://cs.binghamton.edu/~zzhang |
> | Dept. of Computer Science, SUNY at Binghamton |
> --------------------------------------------------
>
>
-Chris
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