File:Penrose rectangle Solomon's knot.png

Self-made graphic, declared to be in public domain, generated from the following PostScript source code:

%!
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6 setlinewidth/C{.8 .9 1}def
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closepath gsave C setrgbcolor
fill grestore stroke}def
/B{-275 -75 moveto 175 -75 lineto
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closepath gsave C setrgbcolor
fill grestore stroke}def
A B gsave 180 rotate A B grestore
/C{.8 1 .9}def gsave 90 rotate
A B 180 rotate A B grestore
0 setlinejoin gsave 4{
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-175 75 lineto  -150 75 lineto stroke
90 rotate}repeat grestore
2{.8 .9 1 setrgbcolor
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fill 0 setgray 10 25 moveto
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140 75 lineto stroke 10 125 moveto
140 125 lineto stroke
180 rotate}repeat showpage
%EOF