fib.c

#include <stdlib.h>
int fib(int n)
{
if (n < 2) return n;
return fib(n - 1) + fib(n - 2);
}
 
int main(int argc, char **argv)
{
fib(35);
return 0;
}
 
/*
% time ./fib
 real    0m0.089s user    0m0.080s sys     0m0.000s

*/

fib.lisp

(defun fib (n)
  (declare (optimize (debug 0) (safety 0) (space 0) (speed 3))
           (fixnum n))
  (labels ((fib (n)
             (if (< n 2)
                 n
                 (the fixnum
                      (+ (fib (1- n))
                         (fib (- n 2)))))))
    (declare (ftype (function (fixnum) fixnum) fib)
             (inline fib))
    (fib n)))

(fib 35)
;=> 9227465
#|------------------------------------------------------------|
Evaluation took:
  0.073 seconds of real time
  0.072005 seconds of total run time (0.072005 user, 0.000000 system)
  98.63% CPU
  175,444,128 processor cycles
  0 bytes consed
  
Intel(R) Core(TM)2 Duo CPU     P8600  @ 2.40GHz
 |------------------------------------------------------------|#


;;; ----------------
;;; w/o inline
(defun fib (n)
  (declare (optimize (safety 0) (speed 3) (debug 0))
           (fixnum n))
  (if (< n 2)
      (the fixnum n)
      (the fixnum
           (+ (fib (- n 1))
              (fib (- n 2))))))
 
(fib 35)
;=> 9227465
#|------------------------------------------------------------|
Evaluation took:
  0.172 seconds of real time
  0.172011 seconds of total run time (0.172011 user, 0.000000 system)
  100.00% CPU
  412,324,533 processor cycles
  0 bytes consed
  
Intel(R) Core(TM)2 Duo CPU     P8600  @ 2.40GHz
 |------------------------------------------------------------|#