rnd-split-number

[AM]

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;how to split randomly a number into "n-parts"
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun rnd-split-number (n &key (total-sum 1.0))
  (let ((values))
    (setq values (loop repeat (- n 1)
                   with val-a = total-sum
                   with val-b
                   collect (setq val-b (random val-a))
                   do (setq val-a (- val-a val-b))))
    (append values (list (- total-sum (sum values))))))


;; examples
(rnd-split-number 5 :total-sum 1.8)

=> (0.26645982 1.47964 0.014375878 0.014122969 0.025401235)

(rnd-split-number 3 :total-sum 9.8)

=> (5.1533704 1.7459779 2.900652)

 

[opmo]

With SEED:

(defun rnd-division (n &key (sum 1.0) seed)
  (do-verbose ("rnd-division")
    (rnd-seed seed)
    (let ((values
           (loop repeat (- n 1)
             with a = sum
             with b
             collect (setf b (random* a :seed (seed)))
             do (setf a (- a b)))))
      (append values (list (- sum (sum values)))))))

(rnd-division 5 :seed 5)
=> (0.0052785673 0.09165209 0.06036401 0.65849 0.1842153)

(rnd-division 3 :sum 9.8 :seed 87)
=> (3.9023237 0.8761092 5.0215673)

 

To add seed to the function use RANDOM* OM function.