function logo(fname)
% LOGO  Routine lays out CU logo inside a ring. 
% Input:  fname   file name onto which the binary data is written 
%                 (size(a),a) where a is a 63*63 'double' array.

cu=['   XXXXXXXXXX        ';...  % The array  a(i,j) is structured as
    '  XXXXXXXXXXXX       ';...  % follows:
    ' XXXXXXXXXXXXXX      ';...  %
    ' XXX        XXX      ';...  %                 ^ x2
    ' XXX        XXX      ';...  %                 |
    ' XXX        XXX      ';...  %   63  + - - - - + - - - - +
    ' XXX  XXXXXX   XXXXXX';...  %                  31
    ' XXX  XXXXXX   XXXXXX';...  %       |         |         |
    ' XXX  XXXXXX   XXXXXX';...  %    .
    ' XXX   XXX  XXX  XXX ';...  %    .  |         |         |
    ' XXX   XXX  XXX  XXX ';...  %       -31                 31
    ' XXX   XXX  XXX  XXX ';...  %    i  + - - - - + - - - - + - > x1
    ' XXXXXXXXXXXXXX  XXX ';...  %
    '  XXXXXXXXXXXX   XXX ';...  %    .  |         |         |
    '   XXXXXXXXXX    XXX ';...  %    .
    '       XXX       XXX ';...  %       |         |         |
    '       XXX       XXX ';...  %                  -31
    '       XXX       XXX ';...  %    1  + - - - - + - - - - +
    '       XXXXXXXXXXXXX ';...  %      
    '        XXXXXXXXXXX  ';...  %       1      .. j ..      63
    '         XXXXXXXXX   '];    %
 
% Create ring
   x1 = [-31:31];
   x2 = [-31:31];
   [ax1,ax2] = meshgrid(x1,x2);
   r = sqrt(ax1.^2+ax2.^2)/31;     % Distance to center of grid
   a = 2*exp(max(-40.0,-6000.0*(r-0.7).^4)).*(1.1-0.75*ax2/31.0);

   % Place CU logo at the middle of the ring; replace value by 1.2 
   % wherever there is an 'X' (or other non-blank symbol) in logo
   a(22:42,22:42) = a(22:42,22:42)+(cu~=' ').*(1.2-a(22:42,22:42));
   a = a/max(max(a));              % Normalize a so in range [0,1]

% Display test object gridpoint-by-gridpoint using 2-D gray scale
   gr = gray;                      % Pick up standard gray map, but swap
   colormap(gr(64:-1:1,:))         % so 0 values (background) becomes light
   pcolor(x1,-x2,a)
   axis equal ; axis tight         % Make the output square
   
% Start new figure; surface plot  plus grey scale image below   
   figure
   colormap(gr(64:-1:1,:))         % Again swap direction of grey scale
   mesh(x1,-x2,a+2)
   axis ([-32 32 -32 32 0 4]) 
   hold on                         % Want to do two plots using the same axes
   pcolor(x1,-x2,a*4)
   shading interp                  % Remove grid lines in base plane 
   hold off
   
% Write to a file logo.bin the size of a followed by its values
   fid = fopen(fname,'w');
   if fid==-1 ; error('File could not be opened') ; end;
   fwrite (fid,[size(a),a(:).'],'double'); 
   fclose (fid);