clear

x1=[1:1000];
y1=(x1/100).^2-3*x1/100+20;

x2=[1:100:1001];
y2= (x2/100).^2-3*x2/100+20+(rand(1,length(x2))-0.5)*20

L=10-rand(1,length(x2))*2;
U=5+rand(1,length(x2))*2

figure(1),plot(x1,y1,x2,y2)

%%
figure(2),plot(x1,y1,'-',x2,y2,'o')

figure(2),plot(x1,y1,'-',x2,y2,'o','linewidth',2,'markerfacecolor','r','markeredgecolor','r'),
axis([0 1000 0 105]),grid on
xlabel('frecuencia \omega [s^{-1}]','fontsize',14),ylabel('amplitud [u. arb.]','fontsize',14),
set(gca,'XTick',[0 200 330  560 800 1000])
set(gca,'FontName','Arial')
set(gca,'FontSize',10)
hold on
errorbar(x2,y2,L,U,'ro')
hold off