;;;series summation 
;;;	GSS_2.LSP  modified GSS_1.LSP
;;;	Sept 24, 2003	Takaya Iwamoto
;;;	geometric series r = 4/1
;;;
(defun c:gss_2 ()
  (setup_gss2)
  (while (= (Yes_or_No "Go to next step ?") "_Y")
    (qtr_quad pnt_a pnt_b pnt_c pnt_d)
    (IF	(= JPG_YES 1) (make_jpg) )
  )
;;;end of while loop
  (alert
    "\n****End****\nInfinite sum of geometirc series (1/4) \nis equal to 1/3"
  )
  (textdisplay "Sum of all yellow" '(1.2 1.5) 0.12 0.)
  (textdisplay "squares is 1/3 ." '(1.2 1.3) 0.12 0.)
  (IF (= JPG_YES 1) (make_jpg) )
  (reset_sysvar)
)
;;;C:gss_1
;;;
;;;
(defun setup_gss2 ()
  (setup_sysvar)
  (setq	pnt_a '(-1 0)
	pnt_b '(1 0)
	pnt_c '(1 2)
	pnt_d '(-1 2)
	lower_left
	 '(-1.25 -0.25)
	upper_right
	 '(2.5 2.25)
	nstep 1
  )
  (make_line_1 "0" 8 pnt_a pnt_b)
  (make_line_1 "0" 8 pnt_b pnt_c)
  (make_line_1 "0" 8 pnt_c pnt_d)
  (make_line_1 "0" 8 pnt_d pnt_a)
  (command "_.zoom" "W" lower_left upper_right)
  (IF (= JPG_YES 1) (make_jpg) )
  (qtr_quad pnt_a pnt_b pnt_c pnt_d)
  (IF (= JPG_YES 1) (make_jpg) )
)
;;;SETUP_GSS2
;;;
;;;
;;;qtr_quad	shade a quarter of a square defined by 3 corner points
;;;
(defun qtr_quad	(pnt_1 pnt_2 pnt_3 pnt_4 / pnt_4 pnt_5 pnt_6)
  (setq	pnt_5	   (mid_point pnt_1 pnt_2)
	pnt_6	   (mid_point pnt_2 pnt_3)
	pnt_7	   (mid_point pnt_3 pnt_4)
	pnt_8	   (mid_point pnt_4 pnt_1)
	pnt_9	   (mid_point pnt_6 pnt_8)
	ref_len	   (distance pnt_1 pnt_5)
	text_size1 (* 0.25 ref_len)
	pnt_text1  (shift_pnt (plt pnt_1 pnt_9 0.1) (list 0 text_size1))
	text_size2 (* 0.6 text_size1)
	pnt_text2  (shift_pnt pnt_text1
			      (list (* 2.75 text_size1) text_size1)
		   )
  )
  (shaded_quad "layer40" pnt_1 pnt_5 pnt_9 pnt_8)
  (shaded_quad "layer110" pnt_5 pnt_2 pnt_6 pnt_9)
  (shaded_quad "layer180" pnt_8 pnt_9 pnt_7 pnt_4)
;;;write text 1/4, 1/16, 1/64, etc in the yellow squares
;;;then increment  nstep by 1
  (setvar "Cecolor" "1")
  (if (= nstep 1)
    (textdisplay " 1/4 " pnt_text1 text_size1 0.)
    (progn
      (textdisplay "(1/4)" pnt_text1 text_size1 0.)
      (textdisplay (itoa nstep) pnt_text2 text_size2 0.)
    )
  )
;;;end of if loop
  (setvar "Cecolor" "BYLAYER")
  (setq nstep (1+ nstep))
;;;redefine a new triangle
  (setq	pnt_a pnt_9
	pnt_b pnt_6
	pnt_d pnt_7
  )
  (make_line_1 "0" 1 pnt_4 pnt_1)
  (make_line_1 "0" 1 pnt_1 pnt_2)
)
;;;QTR_TRIG
;;;
;;;GET_CURTEXT
;;;
(defun get_curtext1 (num)
  (cond
    ((= num 1) "1/4")
    ((= num 2) "1/16")
    ((= num 3) "1/64")
    ((= num 4) "1/256")
    ((= num 5) "1/1024")
    ((= num 6) "1/4096")
    (t "")
  )
)
;;;GET_CURTEXT1	
;;;
(defun get_curtext (num)
  (setq	temp1 "1/"
	temp2 (itoa (expt 4 num))
	temp  (strcat temp1 temp2)
  )

)
;;;GET_CURTEXT