fwd_coil.h File Reference

Single MEG sensor coil or EEG electrode described by a set of weighted integration points in its own coordinate frame. More...

#include "fwd_global.h"
#include <fiff/fiff_coord_trans.h>
#include <Eigen/Core>
#include <memory>

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Classes
class	FWDLIB::FwdCoil
	Single MEG sensor coil or EEG electrode — stores the coil-local frame and the (r_mag, cos_mag, w) integration-point triples that approximate the Biot-Savart surface integral over the coil area. More...

Namespaces
namespace	FWDLIB
	Forward modelling — BEM solver, spherical models, sensor/coil definitions and the lead-field assembly that links current dipoles to MEG/EEG sensor readings.

Functions
constexpr bool	FWDLIB::FWD_IS_MEG_COIL (int x)

Variables
constexpr int	FWDLIB::FWD_COIL_UNKNOWN = 0
constexpr int	FWDLIB::FWD_COILC_UNKNOWN = 0
constexpr int	FWDLIB::FWD_COILC_EEG = 1000
constexpr int	FWDLIB::FWD_COILC_MAG = 1
constexpr int	FWDLIB::FWD_COILC_AXIAL_GRAD = 2
constexpr int	FWDLIB::FWD_COILC_PLANAR_GRAD = 3
constexpr int	FWDLIB::FWD_COILC_AXIAL_GRAD2 = 4
constexpr int	FWDLIB::FWD_COIL_ACCURACY_POINT = 0
constexpr int	FWDLIB::FWD_COIL_ACCURACY_NORMAL = 1
constexpr int	FWDLIB::FWD_COIL_ACCURACY_ACCURATE = 2

Detailed Description

Single MEG sensor coil or EEG electrode described by a set of weighted integration points in its own coordinate frame.

SPDX-License-Identifier: BSD-3-Clause Copyright (c) 2017-2026 MNE-CPP Authors

Author

Christoph Dinh chris.nosp@m.toph.nosp@m..dinh.nosp@m.@mne.nosp@m.-cpp..nosp@m.org; Lorenz Esch loren.nosp@m.z.es.nosp@m.ch@tu.nosp@m.-ilm.nosp@m.enau..nosp@m.de; Juan GPC jgarc.nosp@m.iapr.nosp@m.ieto@.nosp@m.mgh..nosp@m.harva.nosp@m.rd.e.nosp@m.du; Gabriel Motta gabri.nosp@m.elbe.nosp@m.nmott.nosp@m.a@gm.nosp@m.ail.c.nosp@m.om

Since

0.1.0

Date

March 2017

In the Biot-Savart formulation used for MEG, the signal a coil records is the surface integral of the dipole's magnetic field over the coil area projected along the coil normal. The CTF / Elekta coil-definition file approximates that integral as a weighted sum at a handful of integration points; each FwdCoil stores those points as rmag (positions), cosmag (orientations) and w (Gauss-Legendre or trapezoidal weights). A magnetometer reduces to a single point; an axial gradiometer uses two opposing loops with weights ±1; a planar gradiometer uses four points encoding a finite-difference baseline.

For EEG, FwdCoil collapses to a single point with cosmag = (0,0,0) — the electrode is a potential probe, not a field probe — and w carries the reference-electrode subtraction coefficient. The class is a direct refactor of the MNE-C fwdCoilRec struct with raw C-pointers replaced by Eigen matrices.

Definition in file fwd_coil.h.