transcendental-lisp/lisp/compound.lisp

(defun compound (principal interest-rate years)
  (cond
    ((= years 0) principal)
    (t (let ( (previous-principal (compound principal interest-rate (- years 1))) )
            (+ previous-principal
               (/ (+ (* previous-principal
                        interest-rate)
                     50)
                  100)
            )
       )
    )
  )
)