[编程交流] 嵌套线对象的角度

(defun c:test ( / enx lst mat )
   (cond
       (   (not (setq lst (nentselp "\nSelect nested line: ")))
           (princ "\nNo object selected.")
       )
       (   (/= 4 (length lst))
           (princ "\nThe selected object is not nested.")
       )
       (   (/= "LINE" (cdr (assoc 0 (setq enx (entget (car lst))))))
           (princ "\nThe selected object is not a line.")
       )
       (   (setq mat (mapcar 'rcdr (rcdr (caddr lst))))
           (princ (angtos (apply 'angle (mapcar '(lambda ( x ) (mxv mat (cdr (assoc x enx)))) '(10 11)))))
       )
   )
   (princ)
)
;; Reverse cdr  -  Lee Mac
;; Returns all but the last item of a list
(defun rcdr ( l )
   (reverse (cdr (reverse l)))
)
;; Matrix x Vector  -  Vladimir Nesterovsky
;; Args: m - nxn matrix, v - vector in R^n
(defun mxv ( m v )
   (mapcar '(lambda ( r ) (apply '+ (mapcar '* r v))) m)
)
(princ)