%!

1 50 scale
0.05 setlinewidth

10 10 translate

0.5 setgray
newpath
0 -2 moveto
0 2.5 lineto
stroke

(a) == 

0.7 setgray

/f { 1 dict begin      
/x exch def 
x sin 2 mul
end                   
} def

/N 540 def

/x0 0 def 
/xf 1 def

/x x0 def
/dx xf x0 add def

newpath
x x f moveto
N {
/x x dx add def
x x f lineto
} repeat
stroke

(b) ==

newpath
-1 2.5 moveto
540 2.5 lineto
0.9 setgray 
closepath
stroke

(c) ==

/A [ 181 { 0 } repeat ] def 
/n x sin 2 mul 1 add 0.1 div round cvi def

A n
A n get 1 add
put

(d) ==

/k 0 def
/n 0 def

180{
newpath
-1 2.5 moveto
-1 2.5 A n get add lineto
-1 k add 2.5 A n get add lineto
-1 k add 2.5 lineto
/k k 3 add def
/n n 1 add def
0.5 0.5 1 setrgbcolor
fill

} repeat


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