;; | ---------------------------------------------------------------------------
;; | LI_memb
;; | ---------------------------------------------------------------------------
;; | Function : MEMB - member with equal's uncertainty check (diff: real number)
;; | Argument : 'ele'    - Element to check, if in list
;; |            'Lst'    - List to be checked
;; |            'diff'   - A fuzzy tolerance to check for equality 
;; | Returns  : The list index (starting from 0) where the first occurance of 
;; |            'ele' is found else nil
;; | Update   : May 2, 2004
;; | e-mail   : rakesh.rao@4d-technologies.com 
;; | Web      : www.4d-technologies.com
;; | ---------------------------------------------------------------------------


(defun LI_memb(ele Lst diff / len cnt Found)

(if (zerop Diff)
(progn
	(setq Found (member ele Lst))
	(if Found (setq Found T))
)
(progn
	(setq
		len (length Lst)
		cnt 0
		Found nil
	)
	(while (and (< cnt len) (not Found))
		(if (equal ele (nth cnt Lst) diff)
			(setq Found T)
			(setq cnt (1+ cnt))
		)
	)
))
(if Found cnt nil)
)