function seriesfejerlanczos(func,p0,p1,num)

    funcion = str2func(func); 
    close all;
    a0 = double(0);
    a0 = 1/(p1-p0) * quadl(funcion, p0, p1);
    a = repmat(double(0), [1 num]);
    b = repmat(double(0), [1 num]);
    w0 = 2*pi/(p1-p0);
    
    for n=1:num
        func_sin_nx = @(x) funcion(x).* ...
            sin(n*x*w0);
        func_cos_nx = @(x) funcion(x).* ... 
            cos(n*x*w0);   
        a(n) = quadl(func_cos_nx, p0, p1);
        b(n) = quadl(func_sin_nx, p0, p1);        
    end   
        
    a = 2*a/(p1-p0);
    b = 2*b/(p1-p0);    
    
%     figure;stem(0:1:num,[a0 a]);xlabel('los a_k');
%     pause;
%     figure;stem(1:1:num,b);xlabel('los b_k');
%     pause;
    % Representacion grafica de la suma parcial n-esima de Fourier
    
  
        dt = 0.001.*(p1-p0);
        t = p0:dt:p1;
        M=max(funcion(t));
        m=min(funcion(t));

        s = a0.*ones(1,length(t));
        
        for i = 1:num;
          s = s + b(i)*sin(i*t.*w0)+...
                a(i)*cos(i*t.*w0);
          M=max([M s]); m = min([m s]);
        end
        
        for i = 1:num;
          M=max([M b(i)*sin(i*t.*w0)+...
                a(i)*cos(i*t.*w0)]);
            m=min([m b(i)*sin(i*t.*w0)+...
                a(i)*cos(i*t.*w0)]);
        end
        
        M=M+0.1.*(p1-p0);
        m=m-0.1.*(p1-p0);
        
        s = a0.*ones(1,length(t)); 
        f=s;
        figure;hold on; 
                subplot(1,3,1);plot(t,funcion(t),'b');
                axis([p0 p1 m M]);
                xlabel('Seņal x(t)');pause;
                subplot(1,3,2); hold on;
                plot(t,a0.*ones(1,length(t)),'g');axis([p0 p1 m M]);
                xlabel('Sumas parciales de Fejer');pause(0.2);
        for i = 1:num;
              f = f + ((num-i)/num)*(b(i)*sin(i*t.*w0)+...
                a(i)*cos(i*t.*w0));
            plot(t,f,'g');axis([p0 p1 m M]);
            pause(0.2);
        end
        hold off;
        subplot(1,3,3); hold on;
                plot(t,a0.*ones(1,length(t)),'r');
                axis([p0 p1 m M]);
                xlabel('Sumas parciales de Lanczos.');
                pause(0.2);
        for i = 1:num;
          s = s + sin(i*pi/num)/(i*pi/num)*(b(i)*sin(i*t.*w0)+...
                a(i)*cos(i*t.*w0));
            plot(t,s,'r');axis([p0 p1 m M]);
            pause(0.2);
        end
        hold off; 
         hold off;pause;
       % s=s+a0;
      %figure(2);  
   subplot(1,3,1);hold on;
   plot(t,funcion(t),'b');
    plot(t,f,'g', t, s, 'r');
      axis([p0 p1 m M]);
      xlabel('Seņal x(t) y sus aproximaciones Sigma_Nx(t), h_Nx(t)');