%!PS-Adobe-2.0
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%        This Postscript is Copyright (c) 2003, Peter J Billam          %
%     c/o P J B Computing, GPO Box 669, Hobart TAS 7001, Australia      %
%                                                                       %
% Permission is granted  to any individual or institution to use, copy, %
% modify or redistribute this software, so long as it is not resold for %
% profit,  and provided this notice is retained.   Neither Peter Billam %
% nor  P J B Computing  make any representations  about the suitability %
% of this software for any purpose. It is provided "as is", without any %
% express or implied warranty.                http://www.pjb.com.au     %
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% Original of this is http://www.pjb.com.au/comp/free/sample4.ps.txt ...
% See also http://www.pjb.com.au/comp/brownian.html ...
%%EndComments
%%BeginProlog
% edit these lines to suit where brownian.ps and colours.ps are installed
(/home/pjb/ps/lib/brownian.ps) run
(/home/pjb/ps/lib/colours.ps) run
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%%Page: 1 1
%%BeginPageSetup
usertime realtime add srand
%%EndPageSetup

/Times-BoldItalic findfont 14 scalefont setfont 0.0 setgray
160 725 moveto (See  www.pjb.com.au/comp/brownian.html) show

% a brownian curve ...
/x1 150 def /x2 550 def
/y_scale 40 def
/redness 1.3 def   % 0=whitenoise, 1=pinknoise, 2=rednoise
/n_harmonics 100 def
/delta_x x2 x1 sub n_harmonics div 4 div def
x1 x2 y_scale redness n_harmonics new_brownian_curve

30 585 moveto (redness = ) show redness (            ) cvs show
30 555 moveto (n_harmonics = ) show n_harmonics (            ) cvs show

newpath x1 x1 brownian_curve 580 add moveto /x x1 delta_x add def {
	/y x brownian_curve 580 add def
	x y lineto
	/x x delta_x add def x x2 gt { exit } if
} loop
stroke

% a brownian landscape ...
/x1 150 def /x2 550 def
/y1 100 def /y2 400 def
/redness 3.5 def   % 0=whitenoise, 1=pinknoise, 2=rednoise
/z_scale 0.8 def
/n_harmonics 20 def
/delta x2 x1 sub n_harmonics div 4 div def
x1 y1 x2 y2 z_scale redness n_harmonics new_brownian_landscape

30 255 moveto (redness = ) show redness (            ) cvs show
30 225 moveto (n_harmonics = ) show n_harmonics (            ) cvs show

/x x1 def { % plot
   /y y1 def {
      /z x y brownian_landscape def newpath
		[ -1.0 blue 0.0 paleblue .4 white 1.0 mediumgrey ] z rgbinterpolate
		setrgbcolor x y delta dup rectfill
      /y y delta add def y y2 gt { exit } if
   } loop
   /x x delta add def x x2 gt { exit } if
} loop

showpage
%%EOF