;; die_empirical_methods.l
;; CSC 416 - Graci
;; Jacob Peck
;; 20101015

;; defines methods for rolling and determining emprical statistics

;; load in class_die.l and class_accumulator.l
(load "class_die.l")
(load "class_accumulator.l")

;; roll-for-pair method
;; rolls a pair of dice until they match faces
(defmethod roll-for-pair ((d1 die) (d2 die))
  (roll d1)
  (roll d2)
  (if (not (= (die-face d1) (die-face d2)))
    (roll-for-pair d1 d2)
  )
)

;; roll-for-sum method
;; rolls a pair of dice until the faces sum to the given integer
(defmethod roll-for-sum ((d1 die) (d2 die) (v integer))
  (roll d1)
  (roll d2)
  (if (not (= (+ (die-face d1) (die-face d2)) v))
    (roll-for-sum d1 d2 v)
  )
)

;; ep-pair method
;; rolls two dice in trials to determine the empirical probability
;; of rolling a pair
(defmethod ep-pair ((d1 die) (d2 die) (trials integer))
  (let (a)
    (setf a (make-instance 'accumulator))
    (dotimes (x trials)
      (ep-pair-trial d1 d2 a)
    )
    (/ (accumulator-value a) (float trials))
  )
)

;; ep-pair-trial method
;; runs a single trial of ep-pair
(defmethod ep-pair-trial ((d1 die) (d2 die) (a accumulator))
  (forget d1)
  (forget d2)
  (roll-for-pair d1 d2)
  (inc a (length (die-history d1)))
)

;; ep-sum method
;; rolls two dice in trials to determine the empirical probability
;; of rolling a certain sum
(defmethod ep-sum ((d1 die) (d2 die) (v integer) (trials integer))
  (let (a)
    (setf a (make-instance 'accumulator))
    (dotimes (x trials)
      (ep-sum-trial d1 d2 a v)
    )
    (/ (accumulator-value a) (float trials))
  )
)

;; ep-sum-trial method
;; runs a single trial of ep-sum
(defmethod ep-sum-trial ((d1 die) (d2 die) (a accumulator) (v integer))
  (forget d1)
  (forget d2)
  (roll-for-sum d1 d2 v)
  (inc a (length (die-history d1)))
)

;; ep-7-11-doubles method
;; rolls two dice in trials to determine the empirical probability
;; of rolling either a sum of 7 or 11, or a pair
(defmethod ep-7-11-doubles ((d1 die) (d2 die) (trials integer))
  (let (a)
    (setf a (make-instance 'accumulator))
    (dotimes (x trials)
      (ep-7-11-doubles-trial d1 d2 a)
    )
    (/ (accumulator-value a) (float trials))
  )
)

;; ep-7-11-doubles-trial method
;; runs a single trial of ep-7-11-doubles
(defmethod ep-7-11-doubles-trial ((d1 die) (d2 die) (a accumulator))
  (forget d1)
  (forget d2)
  (roll-for-7-11-doubles d1 d2)
  (inc a (length (die-history d1)))
)

;; roll-for-7-11-doubles method
;; rolls a pair of dice until either the sum of the faces is 7 or 11, or
;; the faces match
(defmethod roll-for-7-11-doubles ((d1 die) (d2 die))
  (roll d1)
  (roll d2)
  (if
    (not (or
      (= (die-face d1) (die-face d2)) ; doubles
      (= 7 (+ (die-face d1) (die-face d2))) ; 7's
      (= 11 (+ (die-face d1) (die-face d2))) ; 11's
    ))
    (roll-for-7-11-doubles d1 d2)
  )
)