Simple sine calculation by taylor expansion

simple-sine.el

(defconst if3 (* 2 3))
(defconst if5 (* if3 4 5))
(defconst if7 (* if5 6 7))
(defconst if9 (* if7 8 9))
(defconst if11 (* if9 10 11))

(defun simple-sine (x)
  (unless (eq 'float (type-of x))
    (setf x (float x)))
  (let* ((x2 (* x x))
         (x3 (* x2 x))
         (x5 (* x3 x2))
         (x7 (* x5 x2))
         (x9 (* x7 x2))
         (x11 (* x9 x2)))
    (+ x
       (- (/ x3 if3))
       (/ x5 if5)
       (- (/ x7 if7))
       (/ x9 if9)
       (- (/ x11 if11)))))