COMMENT ⊗   VALID 00004 PAGES
C REC  PAGE   DESCRIPTION
C00001 00001
C00003 00002	delimiters ()
C00005 00003	def tickmarks =
C00020 00004	end
C00021 ENDMK
C⊗;
delimiters ();
def tracingall=tracingcommands:=3;
 tracingedges:=1; tracingtitles:=1; tracingequations:=1; tracingspecs:=2;
	tracingpens:=1; tracingchoices:=1; tracingstats:=2;
 tracingonline:=1;tracingoutput:=1;tracingmacros:=3 enddef;
%tracingall;

def down=(0,-1) enddef;
def up=(0,1) enddef;
def right=(1,0) enddef;
def left=(-1,0) enddef;
def angle primary d = (cosd d, sind d) enddef;

vardef z@#=(x@#,y@#) enddef;

edges e;
e=nulledges;

def draw expr x = addto e contour x withweight 1 enddef;
def erase expr x = addto e contour x withweight -1 enddef;

openwindow 1 from (0,0) to (400,450) at (-100,200);

smoothing:=1; autorounding:=3;

def next =
 display e on 1;
 shipout e;
 e:=nulledges;
 charcode:=charcode+1;
enddef;

hppp:=240/72.27;
vppp:=hppp;
charcode:=96;
h=v=4;

z1=(6h,0); z2=(0,8v); z3=(4h,11v); z4=(10h,8v); z5=(17h,9v); z6=(18h,2v);
z0=(9h,3v);
for n:=1 step 1 until 6: z[n]a-z0 = 2(z[n]-z0); endfor
def tickmarks =
 draw (-5,0)..tension100..(0,0)..tension100..
	(0,-2)..tension100..(-5,-2)..tension100..cycle;
 draw (205,0)..tension100..(200,0)..tension100..
	(200,-2)..tension100..(205,-2)..tension100..cycle;
 enddef;

draw (0,0){angle 30}..(200,0){angle -60} &
      (200,0)..(200,-100){down}..tension10..(0,-100){up}..(0,0) & cycle;
tickmarks; next;
draw (0,0){angle 60}..(200,0){angle -60} &
      (200,0)..(200,-100){down}..tension10..(0,-100){up}..(0,0) & cycle;
tickmarks; next;
draw (0,0){angle120}..(200,0){angle -60} &
      (200,0)..(200,-100){down}..tension10..(0,-100){up}..(0,0) & cycle;
tickmarks; next;
draw (0,0){angle-30}..(200,0){angle -60} &
      (200,0)..(200,-100){down}..tension10..(0,-100){up}..(0,0) & cycle;
tickmarks; next;
erase (0,0){angle 30}..(200,0){angle -60} &
      (200,0)..(200,-100){down}..tension10..(0,-100){up}..(0,0) & cycle;
draw (0,0){angle 60}..(200,0){angle -60} &
      (200,0)..(200,-100){down}..tension10..(0,-100){up}..(0,0) & cycle;
tickmarks; next;
end