Image:Ampersandcurve.png

[edit] License information

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[edit] Source code

% Ampersand curve

function main()

   % linewidth and font size
   lw= 6; 
   fs = 20;

% colors
   red=[0.867 0.06 0.14];
   blue = [0, 129, 205]/256;
   green = [0, 200,  70]/256;
   black = [0, 0, 0];
   white = 0.99*[1, 1, 1];

   % Set up the plotting window
   figure(1); clf; set(gca, 'fontsize', fs, 'linewidth', lw/4);
   hold on; axis equal; grid on;

   N=500;  % number of points (don't make it big, code will be slow)
   Lx1 = -0.3; Lx2 = 1.6; Ly1 = -1.3; Ly2 = -Ly1;
   
   [X, Y]=meshgrid(linspace(Lx1, Lx2, N), linspace(Ly1, Ly2, N));   % X and Y coordinates

   Ncurves = 10;
   A = linspace(0, 1, Ncurves);

   figure(2); clf; hold on; axis equal; axis off;

   x = X; y = Y;
   Z = (y.^2-x.^2).*(x-1).*(2*x-3)-4*(x.^2+y.^2-2*x).^2;
          
%  graph the curves using 'contour' in figure (2)
   figure(2); [c, stuff] = contour(X, Y, Z, [0, 0]);
          
%  extract the curves from c and graph them in figure(1) using 'plot'
%  need to do this kind of convoluted work since plot2svg can't save
%  the result of 'contour' but can save the result of 'plot'   
          
   [m, n] = size(c);
   while n > 0
          
          l=c(2, 1);
          x=c(1,2:(l+1));  y=c(2,2:(l+1)); % get x and y of contours
          figure(1); plot(x, y, 'color', red, 'linewidth', lw/2);
          
          c = c(:, (l+2):n);
          [m, n] = size(c);
                 
   end
   
   figure(1); axis equal; axis ([Lx1, Lx2, Ly1, Ly2]);

   saveas(gcf, 'Ampersandcurve.eps', 'psc2')
%   plot2svg(sprintf('Devils_curve_a=0.0-1.0_b=%0.2g.svg', b));
%   saveas(gcf, sprintf('Devils_curve_a=%0.2g_b=%0.2g.eps', a, b), 'psc2');

[edit] Original upload log

(All user names refer to en.wikipedia)

• 2006-03-09 22:31 Mets501 226×226×8 (2956 bytes) The Ampersand Curve

• Ampersand curve
• Quartic plane curve
• Gallery of curves