MATLAB Implementation of Cubic Spline Interpolation with Algorithm Explanation

This MATLAB .m program implements cubic spline interpolation using a 2D input array A(Nx2). The interpolation method follows the formula: S(x) = A(J) + B(J)*(x - x(J)) + C(J)*(x - x(J))**2 + D(J)*(x - x(J))**3 for x(J) <= x < x(J+1), with detailed coefficient calculation and boundary handling.