plus the 4 band edges, giving a total of L+3 extrema. References Additional references The following additional links provide information on the Parks–McClellan Algorithm, as well as on other research and papers written by James McClellan and Thomas Parks: Chebyshev Approximation for Nonrecursive Digital Filters with Linear Phase Short Help on Parks–McClellan Design of FIR Low Pass Filters Using MATLAB Intro to DSP The MathWorks MATLAB documentation ELEC4600 Lecture Notes (original link, archived on 15 Apr 2012) C Code Implementation (LGPL License) – By Jake Janovetz Revised and expanded algorithm McClellan, Parks, & Rabiner, 1975; Fortran code. Digital signal processing Filter theory