the function code:
if true
% code
function y = mylagrange(xdp, j, x)
% input: xdp = abscissas of data points
% j = evaluate j-th lagrange polynomial
% x = points where polynomial or derivative is evaluated:
% scalar, vector, or matrix
% output: y = ell_j(x)
ndp = length(xdp);
y = 1; % or y = ones(size(x))
for k = 1:ndp
if k ~= j
y = y .* (x - xdp(k))/(xdp(j) - xdp(k));
end
end
end
end