clear all; close all;

%  Get data:

x=-1:0.2:1;  y=1./(1.+25*x.*x); n=length(x);

% Evaluate y = sqrt(x) between 0 and 10 using the Lagrange polynomial with
% step size 0.2

x1=-1:0.05:1; N2=length(x1);

for i=1:N2,
  yp(i) = lagrange1(n,x,y,x1(i));
  true(i) = 1/(1 + 25*x1(i)^2);
end

plot(x1,true,x1,yp,'o')
title('Exact and interpolated results')
figure(2); plot(x1,yp-true); title('Error plot')
hold; y2=0*y; plot(x,y2,':')