% illustration of tangent bundle function main()     a=0; b=2*pi; N = 100;    X=linspace(a, b, N);    Y=sin(X);    % the function to plot    XT = 0*X+1;    YT = cos(X); % derivative     Theta = linspace(a, b, N);    X =   cos(Theta); Y  = sin(Theta);    XT = -sin(Theta); YT = cos(Theta);    ll = 2.5; % length of lines perpendicular to the curve        thin_line = 2;    thick_line = 4;     %  will draw lines tangent to the graph of Y=f(X) at %  points separted by length of 'spacing'    spacing = 0.04;    M = floor(spacing*N);   % colors    red=[0.867 0.06 0.14];    blue = [0, 129, 205]/256;    green = [0, 200,  70]/256;    gray=0.8*[1, 1, 1];        figure(1); clf; hold on; axis equal; axis off;    figure(2); clf; hold on; axis equal; axis off; view(18, 36);  % plot the curve    figure(1); s=0.95; plot (s*X, s*Y,      'linewidth', thick_line, 'color', blue);    figure(2); plot3(X, Y, 0*X, 'linewidth', thick_line, 'color', blue);  % plot the lines    for k=1:N              p = (k-1)*M+2;       if p >= N 	 break;       end        figure(1);       x0 = X(p); y0=Y(p); mx = XT(p); my = YT(p);       plot([x0-mx*ll, x0+mx*ll], [y0-my*ll, y0+my*ll], 'color', red, 'linewidth', thin_line)                     figure(2);       plot3([X(p), X(p)], [Y(p), Y(p)], [-ll, ll], 'color', red, 'linewidth', thin_line) 	      end      % save to disk as eps and svg    figure(1); saveas(gcf, 'Tangent_bundle1.eps', 'psc2'); plot2svg('Tangent_bundle1.svg')    figure(2); saveas(gcf, 'Tangent_bundle2.eps', 'psc2'); plot2svg('Tangent_bundle2.svg')