Thread: Periodicity of rand

I'm not sure how much this helps determine periodicity, but here is a way to at least get the same sequence...
from rand(3): pseudo-random number generator - Linux man page

Code:

POSIX.1-2001 gives the following example of an implementation of rand()
       and srand(), possibly useful when one needs the same  sequence  on  two
       different machines.

           static unsigned long next = 1;

           /* RAND_MAX assumed to be 32767 */
           int myrand(void) {
               next = next * 1103515245 + 12345;
               return((unsigned)(next/65536) % 32768);
           }

           void mysrand(unsigned seed) {
               next = seed;
           }

> I thought that the rand function was just defined in the stdlib.h library
It is, but each compiler writer supplies their own IMPLEMENTATION of the code behind stdlib.h.
You need to find glibc, and find out how it implements rand().