Exercise 1 Write a function Lagrange.interp.m that computes the Lagrangian interpolant of a given set of data points (zi, yi),-1, 2, The function should be of the form function [y] Lagrange interp(xi,yi,x) Input: xi: vector of interpolation nodes yi: vector of data points at interpolation nodes x: vector of points at which we evaluate the polynomial interpolant Output: Hint: Compare the output of your function with the output of the Matlab/Octave built-in function, y_polyval (polyf it (xi , yi , length (x1)-1) ,x) (see the Matlab/Octave documentation)