x=[-1:0.2:1]';
y=exp(-100*x.^2);
c=polyfit(x,y,10);
xp=[-1:0.01:1]';
yp=polyval(c,xp);
plot(x,y,'o',xp,yp)
title('Runges fenomen')
xlabel('x')
ylabel('y=e^{-100x^2}')