%!PS
% Draw a spiral of squares
% Illustrates: for-loop, rotate, translate, scale.
% Joseph O'Rourke

3 setlinewidth
1 0 0 setrgbcolor

/inch {72 mul} def

4.25 inch 5.5 inch translate
0.25 0.25 scale

% Draw a 1x1 square, lower left corner at origin
/square {
    newpath
    0 0 moveto
    1 inch 0 lineto
    1 inch 1 inch lineto
    0 1 inch lineto
    closepath
    stroke
} def

% Draw n squares
/n 24 def

gsave

1 1 n {
    % bind loop variable to x
    /x exch def
    square
    30 rotate
    0 x 10 mul translate
    1.1 1.1 scale
} for

grestore

% circle the origin
0 0 1 setrgbcolor
0 0 20 0 360 arc
stroke

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