% Illustration of approximating the Dirac delta function with gaussians.  function main()     r = 3; % the power in the Bernoulli inequality        % KSmrq's colors    red    = [0.867 0.06 0.14];    blue   = [0, 129, 205]/256;    green  = [0, 200,  70]/256;    yellow = [254, 194,   0]/256;    white = 0.99*[1, 1, 1];    % Set up the grid and other parameters    N = 300;    A = -2; B = 2;     C=-1; D = 6;     X = linspace(A, B, N);        % Set up the figure    lw = 3; % linewidth    fs = 18; % font size     for p=1:10        a=1/p;        % gaussian       Y=(1/(a*sqrt(pi)))*exp(-X.^2/a^2);        figure(1); clf;         set(gca, 'fontsize', fs);       set(gca, 'linewidth', 0.4*lw)       hold on;              plot_axes (A, B, C, D, lw/1.5);              plot(X, Y, 'color', blue, 'linewidth', lw);              axis equal; axis([A, B, C, D]);               set(gca, 'XTick', [-2, -1, 0, 1, 2]) % text labels on the x axis       grid on;              H=text(B-1.5, D-0.5, sprintf('a=1/%d', p), 'fontsize', fs);        % save to disk       file = sprintf('Frame%d.eps', 1000+p);       disp(file);       saveas(gcf, file, 'psc2')              pause(0.1);     end   % Converted to gif with the command  % convert -antialias -density 100 -delay 20 -loop 10000 Frame10* Dirac_function_approximation.gif  % then scaled in Gimp        function plot_axes (A, B, C, D, lw)        gray = 0.5*[1, 1, 1];        plot([A B], [0, 0], 'linewidth', lw, 'color', gray);    plot([0, 0], [C, D], 'linewidth', lw, 'color', gray);