; Adds two numbers and returns the sum. (defun add (x y) (+ x y)) ; Returns the minimum number from a list. (defun minimum (L) (apply 'min L)) ; Function that returns the average number of a list of numbers. (defun average (number-list) (let ((total 0)) (dolist (i number-list) (setf total (+ total i))) (/ total (length number-list)))) ; Function that returns how many times an element occures in a list. (defun count-of (x elements) (let ((n 0)) (dolist (i elements) (if (equal i x) (setf n (+ n 1)))) n)) ; Returns the factorial of a number using an interative method. (defun iterative-factorial (num) (let ((factorial 1)) (dotimes (run num factorial) (setf factorial (* factorial (+ run 1)))))) ; Using a recursive method, this function returns the factorial of a number. (defun recursive-factorial (n) (if (<= n 0) 1 (* n (recursive-factorial (- n 1))))) ; This function calculates a number from fibonacci sequences and returns it. (defun fibonacci (num) (if (or (zerop num) (= num 1)) 1 (let ((F1 (fibonacci (- num 1))) (F2 (fibonacci (- num 2)))) (+ F1 F2)))) ; Takes a list and returns all elements that occur on and after a symbol. (defun trim-to (sym elements) (member sym elements)) ; Returns the ackermann of two numbers. (defun ackermann (num1 num2) (cond ((zerop num1) (1+ num2)) ((zerop num2) (ackermann (1- num1) 1)) (t (ackermann (1- num1) (ackermann num1 (1- num2)))))) ; This function defines test code for each previous function. (defun test () (print (add 3 1)) (print (average '(1 2 3 4 5 6 7 8 9))) (print (minimum '(5 78 9 8 3))) (print (count-of 'a '(a '(a c) d c a))) (print (iterative-factorial 5)) (print (iterative-factorial 4)) (print (fibonacci 6)) (print (trim-to 'c '(a b c d e))) (print (ackermann 1 1))) ; Calls the test function. (test)

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