parksmcclellan.h File Reference

Parks–McClellan equiripple FIR design via the Remez exchange algorithm. More...

#include "dsp_global.h"
#include <Eigen/Core>
#include <QObject>

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Classes
class	UTILSLIB::ParksMcClellan
	Parks-McClellan equiripple FIR filter design algorithm (Remez exchange). More...

Namespaces
namespace	UTILSLIB
	Shared utilities (I/O helpers, spectral analysis, layout management, warp algorithms).

Detailed Description

Parks–McClellan equiripple FIR design via the Remez exchange algorithm.

SPDX-License-Identifier: BSD-3-Clause Copyright (c) 2026 MNE-CPP Authors

Author

Christoph Dinh chris.nosp@m.toph.nosp@m..dinh.nosp@m.@mne.nosp@m.-cpp..nosp@m.org

Since

2.0.0

Date

March 2026

The Parks–McClellan algorithm computes the optimal linear-phase FIR filter that minimises the maximum (Chebyshev / minimax) deviation between the desired and the realised frequency response over a set of pass- and stop-band intervals. The solution is uniquely characterised by the equiripple property: at least N+2 alternations of the error function occur on the union of pass- and stop-bands, where N is the filter order.

The implementation here is a direct C++ translation of the original Fortran code of McClellan, Parks and Rabiner. It exchanges trial extremal frequencies until the alternation condition is satisfied, then constructs the impulse response by interpolating the resulting Chebyshev polynomial back to the time domain. Practical limits: 9 ≤ NumTaps ≤ 128, transition width 0.02–0.30 (normalised to π), and odd tap counts for high-pass and notch types so a linear-phase type-I structure is realisable.

Used as one of the design back-ends of FilterKernel and ultimately of FirFilter; cosine-tapered designs are the alternative when speed matters more than equiripple optimality.

Definition in file parksmcclellan.h.