Mine

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
/* This code is not meant to be efficient. It is meant
** to demonstrate the use of the FLI.
*/
/* this does all the work, not exported */
static int worker(double *x, double *y)
{

y=x+1;
return 0;
}
/* exported wrapper, all double * arguments, calls the real
** function with whatever data types it expects
*/
int caller(double *x, double *y)
{
return worker(x,y);
}