[LISP程序]：帮我看一下我这段程序那里错的

ssgmyvvfb

输入圆心与半径，边数，做出多边形弧。
谁能帮我看一下我这些代码错在那里。我按我的思路做下来决的没有错，可是运行起来就有错。晕死了，帮一下小弟好吗？
(defun c:lin2()
  (setvar "cmdecho" 0)
  (setq os (getvar "osmode"))
  (setvar "osmode" 0)
  (setq cen (getpoint "\n请输入圆心"))
  (setq rr (getdist cen "\n请输入半径"))
  (setq n (getint "\n请输入偶数多边形<6>"))
  (command "circle" cen rr)
  (if (null n) (setq n 6))
  (if (= (rem n 2) 0)
    (setq ang (/ (* pi 2) n))
    (setq pt1 (polar cen 0 rr))
    (setq pt2 (polar cen (/ pi 2) rr))
    (setq ang1 (/ pi 3))
    (setq ang2 (- pi pi))
    (repeat n
      (command "arc" pt2 "e" pt1 "a" 180)
      (setq ang1 (- ang1 ang))
      (setq ang2 (- ang2 ang))
      (setq pt2 (polar cen ang1 rr))
      (setq pt1 (polar cen ang2 rr))
    )
    (alert "请输入偶数！")
    )
  (setvar "osmode" os)
  (prin1)
  )

841594

(if (= (rem n 2 0))
(progn
...
) ;progn
) ; if

zxq0220

更改后的程序：
[php]
(defun c:lin2()
(setvar "cmdecho" 0)
(setq os (getvar "osmode"))
(setvar "osmode" 0)
(setq cen (getpoint "\n请输入圆心"))
(setq rr (getdist cen "\n请输入半径"))
(setq n (getint "\n请输入多边形边数<6>"))
(command "circle" cen rr)
(if (null n) (setq n 6))
(if (> n 2) (PROGN
(setq ang (/ (* pi 2) n))
(setq pt1 (polar cen 0 rr))
(setq pt2 (polar cen ANG rr))
(command "arc" pt2 "e" pt1 "a" 180)
(COMMAND "ARRAY" "L" "" "P" CEN N "" "Y")
)
(alert "多边形边数太小！")
)
(setvar "osmode" os)
(prin1)
)
[/php]

狂刀

学会用vl调试，可检测你自己的程序在哪里出差