Time for an 2014 update…

Task/Fibonacci-sequence/Common-Lisp/fibonacci-sequence-1.lisp

@@ -1,4 +1,8 @@
-(defun fibonacci-recursive (n)
-  (if (< n 2)
-      n
-     (+ (fibonacci-recursive (- n 2)) (fibonacci-recursive (- n 1)))))
+(defun fibonacci-iterative (n &aux (f0 0) (f1 1))
+  (case n
+    (0 f0)
+    (1 f1)
+    (t (loop for n from 2 to n
+             for a = f0 then b and b = f1 then result
+             for result = (+ a b)
+             finally (return result)))))

Task/Fibonacci-sequence/Common-Lisp/fibonacci-sequence-2.lisp

@@ -1,8 +1,7 @@
-(defun fibonacci-iterative (n &aux (f0 0) (f1 1))
-  (case n
-    (0 f0)
-    (1 f1)
-    (t (loop for n from 2 to n
-             for a = f0 then b and b = f1 then result
-             for result = (+ a b)
-             finally (return result)))))
+(defun fibonacci (n)
+  (let ((a 0) (b 1) (c n))
+    (loop for i from 2 to n do
+	 (setq c (+ a b)
+	       a b
+	       b c))
+    c))

Task/Fibonacci-sequence/Common-Lisp/fibonacci-sequence-3.lisp

@@ -1,4 +1 @@
-(defun fibonacci-tail-recursive ( n &optional (a 0) (b 1))
-  (if (= n 0)
-      a
-      (fibonacci-tail-recursive (- n 1) b (+ a b))))
+(loop for x = 0 then y and y = 1 then (+ x y) do (print x))

Task/Fibonacci-sequence/Common-Lisp/fibonacci-sequence-4.lisp

@@ -1,9 +1,4 @@
-(defun fib (n &optional (a 1) (b 0) (p 0) (q 1))
-    (if (= n 1) (+ (* b p) (* a q))
-     (fib (ash n -1)
-          (if (evenp n) a (+ (* b q) (* a (+ p q))))
-          (if (evenp n) b (+ (* b p) (* a q)))
-          (+ (* p p) (* q q))
-          (+ (* q q) (* 2 p q))))) ;p is Fib(2^n-1), q is Fib(2^n).
-
-(print (fib 100000))
+(defun fibonacci-recursive (n)
+  (if (< n 2)
+      n
+     (+ (fibonacci-recursive (- n 2)) (fibonacci-recursive (- n 1)))))

Task/Fibonacci-sequence/Common-Lisp/fibonacci-sequence-5.lisp

@@ -1 +1,4 @@
-(loop for x = 0 then y and y = 1 then (+ x y) do (print x))
+(defun fibonacci-tail-recursive ( n &optional (a 0) (b 1))
+  (if (= n 0)
+      a
+      (fibonacci-tail-recursive (- n 1) b (+ a b))))

Task/Fibonacci-sequence/Common-Lisp/fibonacci-sequence-6.lisp

@@ -0,0 +1,9 @@
+(defun fib (n &optional (a 1) (b 0) (p 0) (q 1))
+    (if (= n 1) (+ (* b p) (* a q))
+     (fib (ash n -1)
+          (if (evenp n) a (+ (* b q) (* a (+ p q))))
+          (if (evenp n) b (+ (* b p) (* a q)))
+          (+ (* p p) (* q q))
+          (+ (* q q) (* 2 p q))))) ;p is Fib(2^n-1), q is Fib(2^n).
+
+(print (fib 100000))