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%!PS-Adobe-3.0

1 setlinewidth
1 setlinecap

/len 200 def		        % screen length in centiinches
/len2 len 1 div def


600 600 translate


% ******************************** Fig. (b):

/theta1 0 def		        % angle of screen A
/theta2 5 def		        % angle of screen B
/rot 0 def		            % general rotation to prevent printer artifacts
/p1 3 def		            % period of screen A
/p2 3 def		            % period of screen B
/p1y 3 1 mul def		    % period of screen A (in the perpendicular direction)
/p2y 3 1 mul def		    % period of screen B (in the perpendicular direction)
/xshift1 0.5 p1 mul def		% x period-shift of screen A (e.g. 0.5)
/yshift1 0 p1y mul def		% y period-shift of screen A (e.g. 0.5)
/xshift2 0.5 p2 mul def		% x period-shift of screen B
/yshift2 0 p2y mul def		% y period-shift of screen B


% Draw screen A:
gsave
theta1 rot add rotate
/xsh len2 p1y div round xshift1 mul neg def
0 p1y len {		            % draw rows of dots
    newpath
	/ysave exch len2 p1y div round p1y mul yshift1 sub sub def
	0 p1 len {		        % draw a row of dots
        len2 p1 div round p1 mul xsh sub sub ysave moveto
        0 0 rlineto
    } for
	stroke
    /xsh xsh xshift1 add def
} for
grestore

% Draw screen B:
gsave
theta2 rot add rotate
/xsh len2 p2y div round xshift2 mul neg def
0 p2y len {		                % draw rows of dots
    newpath
	/ysave exch len2 p2y div round p2y mul yshift2 sub sub def
	0 p2 len {	            	% draw a row of dots
        len2 p2 div round p2 mul xsh sub sub ysave moveto
        0 0 rlineto
    } for
	stroke
    /xsh xsh xshift2 add def
} for
grestore

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