Lagrange Interpolation Coefficient Symmetry
As shown in [502, §3.3.3], directly substituting into Eq.(4.7) derives the following coefficient symmetry property for the interpolation coefficients (impulse response) of a Lagrange fractional delay filter:
where is the order of the interpolator. Thus, the interpolation coefficients for delay are the ``flip'' (time reverse) of the coefficients for delay .
Matlab Code for Lagrange Interpolation
Explicit Lagrange Coefficient Formulas