Lagrange polynomial

Lagrange form of the interpolation polynomial

% Polynomial Interpolation Problem: Lagrange Form
% x and y are vectors with the same dimensions
% Given n points: (x_k,y_k) k = 1,2,...n
% this function finds a polynomial P(x) of degree less
% than n such that P(x_k) = y_k
% --
% Remarks:
% The resulting polynomial is displayed in symbolic notation
% --
% Example
% x=[0 1 2 3 4 5 6 7];
% y=[4 -6 -1 16 -2 6 12 17];
% pol=show_polinterp(x,y);
% --
% x=[1 2 3 4 5 6 7];
% y=1+x.^3-x.^6;
% pol=show_polinterp(x,y);
%
% For evaluating pol, try
% subs(pol,x), it will return vector y
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