Introduction

In the previous chapter, we derived the interpolation formula when the values of the function are given at equidistant tabular points $x_0, x_1, \ldots, x_N.$ However, it is not always possible to obtain values of the function, $y=f(x)$ at equidistant interval points, $x_i.$ In view of this, it is desirable to derive an interpolating formula, which is applicable even for unequally distant points. Lagrange's Formula is one such interpolating formula. Unlike the previous interpolating formulas, it does not use the notion of differences, however we shall introduce the concept of divided differences before coming to it.