Checked content

File:Torus illustration.png

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 This chart was created with MATLAB.
Description Illustration of torus
Date 01:12, 13 July 2008 (UTC)
Source self-made, with MATLAB
Author Oleg Alexandrov
Public domain I, the copyright holder of this work, release this work into the public domain. This applies worldwide.
In some countries this may not be legally possible; if so:
I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.


Converted to SVG.svg This math image could be recreated using vector graphics as an SVG file. This has several advantages; see Commons:Media for cleanup for more information. If an SVG form of this image is already available, please upload it. After uploading an SVG, replace this template with {{ vector version available|new image name.svg}}.

Source code 

% illustration of a torus, obtained as an isosurface
function main()
 
   % big and small radii of the torus
   R = 3; r = 1; 
 
   Kb = R+r;
 
   h = 0.1; % h is the grid size. Smaller h means prettier picture.
 
   X = (-Kb-h):h:(Kb+h);   m = length(X);
   Y = (-Kb-h):h:(Kb+h);   n = length(Y);
   Z = (-r-h):h:(r+h);     k = length(Z);
 
   W = zeros(m, n, k); % the zero level set of this function will be the desired shape
 
   for i=1:m
      for j=1:n
         x = X(i);
         y = Y(j); 
         W(i, j, :) = (sqrt(x^2+y^2)-R)^2 + Z.^2-r^2; % torus eqn, vectorize in Z
      end
   end
 
   figure(4); clf; hold on; axis equal; axis off;
 
   H = patch(isosurface(W, 0));
   isonormals(W, H);
 
   light_green=[184, 224, 98]/256;
 
   % set some propeties
   set(H, 'FaceColor', light_green, 'EdgeColor','none', 'FaceAlpha', 1);
   set(H, 'SpecularColorReflectance', 0.1, 'DiffuseStrength', 0.8);
   set(H, 'FaceLighting', 'phong', 'AmbientStrength', 0.3);
   set(H, 'SpecularExponent', 108);
 
   daspect([1 1 1]);
   axis tight;
   colormap(prism(28))
 
  % viewing angle
   view(-146, 32);
 
  % add in a source of light
   camlight (-10, 54); lighting phong;
 
  %save as png
  print('-dpng', '-r400', sprintf('Torus_illustration.png'));
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