How to use Mersenne Twister random number generati

Question

I want to use one of the Mersenne Twister C libraries (e.g. tinymt, mtwist, or libbrahe) so I can use it as a seed for rand() in a C program. I wasn't able to find a simple minimalistic example on how to do this.

I got this far with the mtwist package, but through pjs's comments I've realized that this is the wrong way to do it:

#include <stdio.h>
#include <stdlib.h>
#include "mtwist.h"

int main() {
    uint32_t random_value;

    random_value = mt_lrand();
    srand(random_value);
    printf("mtwist random: %d; rand: %d\n", random_value, rand());

    return 0;
}

(Originally I wrote that this code wouldn't compile, but thanks to Carl Norum's answer I was able to compile it afterall.)

Could anyone give me a simple example on how to properly generate random numbers with any Mersenne Twister C library?

Answer 1

That's not a compiler error, it's a linker error. You're missing the appropriate -l flag to link the library you're using. Your compiler invocation should look something like:

cc -o example example.c -lmtwist

I just took a quick look at the mtwist page you linked to, and it appears to be distributed just as source, not as a library. In that case, adding the appropriate implementation file to your command line should work:

cc -o example example.c mtwist.c

But you probably should look into a make-based solution that builds a real library out of the mtwist code.

Answer 2

Here's a demo of how to use the mtwist implementation of Mersenne Twister:

#include <stdio.h>
#include <stdlib.h>
#include "mtwist.h"

int main(void) {
   int i;
   mt_seed();
   for(i = 0; i < 10; ++i) {
      printf("%f\n", mt_ldrand());
   }
   return EXIT_SUCCESS;
}

Compiled and run as follows:

[pjs@amber:mtwist-1.4]$ gcc run-mtwist.c mtwist.c
[pjs@amber:mtwist-1.4]$ ./a.out
0.817330
0.510354
0.035416
0.625709
0.410711
0.980872
0.965528
0.444438
0.705342
0.368748
[pjs@amber:mtwist-1.4]$