function main()   thickness1=2; thickness2=1; arrowsize=5; arrow_type=2; ball_rad=0.012;   blue=[0, 0, 1]; fontsize=25; dist=0.005;      a=-1.4; b=-a;   h=0.01;   X=a:h:b;   Y=zeros(length(X), 1);   for i=1:length(X)      x=X(i);      if x < 1 & x > -1 Y(i)=exp(-1/(1-x^2));      end   end   figure(1);  clf; hold on; axis equal; axis offarrow([a 0], [b+0.2, 0], thickness2, arrowsize, pi/8,arrow_type, [0, 0, 0])arrow([0 -0.1], [0 2.*max(Y)], thickness2, arrowsize, pi/8,arrow_type, [0, 0, 0])plot(X, Y, 'linewidth', thickness1, 'color', [0 0 1]);arrow([b+0.1 0], [b+0.2, 0], thickness2, arrowsize, pi/8,arrow_type, [0, 0, 0])ball(1, 0, ball_rad, blue); ball(-1, 0, ball_rad, blue);place_text_smartly(1, fontsize, 6, dist, '1');place_text_smartly(-1, fontsize, 6, dist, '-1');saveas(gcf, 'mollifier_illustration.eps', 'psc2')function place_text_smartly (z, fs, pos, d, tx) p=cos(pi/4)+sqrt(-1)*sin(pi/4); z = z + p^pos * d * fs;  shiftx=0.0003; shifty=0.002; x = real (z); y=imag(z);  H=text(x+shiftx*fs, y+shifty*fs, tx); set(H, 'fontsize', fs, 'HorizontalAlignment', 'c', 'VerticalAlignment', 'c')function ball(x, y, r, color)   Theta=0:0.1:2*pi;   X=r*cos(Theta)+x;   Y=r*sin(Theta)+y;   H=fill(X, Y, color);   set(H, 'EdgeColor', color);function arrow(start, stop, thickness, arrowsize, sharpness, arrow_type, color)%  draw a line with an arrow at the end%  start is the x,y point where the line starts%  stop is the x,y point where the line stops%  thickness is an optional parameter giving the thickness of the lines   %  arrowsize is an optional argument that will give the size of the arrow %  It is assumed that the axis limits are already set%  0 < sharpness < pi/4 determines how sharp to make the arrow%  arrow_type draws the arrow in different styles. Values are 0, 1, 2, 3.   %       8/4/93    Jeffery Faneuff%       Copyright (c) 1988-93 by the MathWorks, Inc.%       Modified by Oleg Alexandrov 2/16/03      if nargin <=6      color=[0, 0, 0];   end      if (nargin <=5)      arrow_type=0;   % the default arrow, it looks like this: ->   end      if (nargin <=4)      sharpness=pi/4; % the arrow sharpness - default = pi/4   end   if nargin<=3      xl = get(gca,'xlim');      yl = get(gca,'ylim');      xd = xl(2)-xl(1);                  yd = yl(2)-yl(1);                  arrowsize = (xd + yd) / 2;   % this sets the default arrow size   end   if (nargin<=2)      thickness=0.5; % default thickness   end         xdif = stop(1) - start(1);   ydif = stop(2) - start(2);   if (xdif == 0)      if (ydif >0)  theta=pi/2;      else theta=-pi/2;      end   else      theta = atan(ydif/xdif);  % the angle has to point according to the slope   end   if(xdif>=0)      arrowsize = -arrowsize;   end   if (arrow_type == 0) % draw the arrow like two sticks originating from its vertex      xx = [start(1), stop(1),(stop(1)+0.02*arrowsize*cos(theta+sharpness)),NaN,stop(1),...    (stop(1)+0.02*arrowsize*cos(theta-sharpness))];      yy = [start(2), stop(2), (stop(2)+0.02*arrowsize*sin(theta+sharpness)),NaN,stop(2),...    (stop(2)+0.02*arrowsize*sin(theta-sharpness))];      plot(xx,yy, 'LineWidth', thickness, 'color', color)   end   if (arrow_type == 1)  % draw the arrow like an empty triangle      xx = [stop(1),(stop(1)+0.02*arrowsize*cos(theta+sharpness)), ...    stop(1)+0.02*arrowsize*cos(theta-sharpness)];      xx=[xx xx(1) xx(2)];            yy = [stop(2),(stop(2)+0.02*arrowsize*sin(theta+sharpness)), ...    stop(2)+0.02*arrowsize*sin(theta-sharpness)];      yy=[yy yy(1) yy(2)];      plot(xx,yy, 'LineWidth', thickness, 'color', color)      %     plot the arrow stick      plot([start(1) stop(1)+0.02*arrowsize*cos(theta)*cos(sharpness)], [start(2), stop(2)+ ...    0.02*arrowsize*sin(theta)*cos(sharpness)], 'LineWidth', thickness, 'color', color)         end      if (arrow_type==2) % draw the arrow like a full triangle      xx = [stop(1),(stop(1)+0.02*arrowsize*cos(theta+sharpness)), ...    stop(1)+0.02*arrowsize*cos(theta-sharpness),stop(1)];            yy = [stop(2),(stop(2)+0.02*arrowsize*sin(theta+sharpness)), ...    stop(2)+0.02*arrowsize*sin(theta-sharpness),stop(2)];      %     plot the arrow stick      plot([start(1) stop(1)+0.01*arrowsize*cos(theta)], [start(2), stop(2)+ ...    0.01*arrowsize*sin(theta)], 'LineWidth', thickness, 'color', color)      H=fill(xx, yy, color);% fill with black      set(H, 'EdgeColor', 'none')   end   if (arrow_type==3) % draw the arrow like a filled 'curvilinear' triangle      curvature=0.5; % change here to make the curved part more curved (or less curved)      radius=0.02*arrowsize*max(curvature, tan(sharpness));      x1=stop(1)+0.02*arrowsize*cos(theta+sharpness);      y1=stop(2)+0.02*arrowsize*sin(theta+sharpness);      x2=stop(1)+0.02*arrowsize*cos(theta)*cos(sharpness);      y2=stop(2)+0.02*arrowsize*sin(theta)*cos(sharpness);      d1=sqrt((x1-x2)^2+(y1-y2)^2);      d2=sqrt(radius^2-d1^2);      d3=sqrt((stop(1)-x2)^2+(stop(2)-y2)^2);      center(1)=stop(1)+(d2+d3)*cos(theta);      center(2)=stop(2)+(d2+d3)*sin(theta);      alpha=atan(d1/d2);      Alpha=-alpha:0.05:alpha;      xx=center(1)-radius*cos(Alpha+theta);      yy=center(2)-radius*sin(Alpha+theta);      xx=[xx stop(1) xx(1)];      yy=[yy stop(2) yy(1)];%     plot the arrow stick      plot([start(1) center(1)-radius*cos(theta)], [start(2), center(2)- ...    radius*sin(theta)], 'LineWidth', thickness, 'color', color);      H=fill(xx, yy, color);% fill with black      set(H, 'EdgeColor', 'none')   end