I try to put a seed as an option in this function with a default value of nil or no seed , how may i add it as optional 

 

Thanks  Patrick  

 

(defun patkaos ( seed lambda long )
 (let ((res (cons seed nil)) (xn seed))
    (dotimes (n long res) (setf res (cons (setf xn (* lambda xn (- 1 xn))) res)))
    (reverse res)))

Check the RND-SEED document.

 

i looked at it and i tried to put it in the function , but without success 

 

This is what i did 

 

(defun patkaos (  lambda long &key seed  )

(rnd-seed seed )
 (let ((res (cons seed nil)) (xn seed))
    (dotimes (n long res) (setf res (cons (setf xn (* lambda xn (- 1 xn))) res)))
    (reverse res)))

 

when i evaluate this is what i gat 

 

Error: floating-point-overflow detected
>        performing * on (-2.5452163E+36 2.5452163E+36)
> While executing: ccl::*-2, in process Listener-1(7).
> Type cmd-. to abort, cmd-\ for a list of available restarts.
> Type :? for other options.

 

 

Thanks Patrick

I get it work now Thank you 

 

Patrick