Introduction - If you have any usage issues, please Google them yourself
Maximally-Flat FIR Approximation (Lagrange Interpolation)
Lagrange interpolation is a time-domain approach that leads to a special case of polynomial-based filters. The output signal is approximated with a polynomial of degree M. The simplest case (M=1) corresponds to linear interpolation. Let's design and analyze several linear fractional delay filters that will split the unit delay by various fractions: