function yint = Lagrange(x,y,xx) % input: % x = independent variable % y = dependent variable % xx = value of independent variable at which the % interpolation is calculated % output: % yint = interpolated value of dependent variable n = length(x); if length(y)~=n, error('x and y must be same length'); end s = 0; for i = 1:n product = y(i); for j = 1:n if i ~= j product = product*(xx-x(j))/(x(i)-x(j)); end end s = s+product; end yint = s; end