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InvDipoleForward

Namespace: INVLIB  ·  Library: Inverse Library

#include <inv/inv_dipole_forward.h>

class INVLIB::InvDipoleForward

Implements InvDipoleForward (Replaces *dipoleForward,dipoleForwardRec struct of MNE-C fit_types.h).

Stores forward field matrices and SVD decomposition for magnetic dipole fitting.

For each set of candidate dipole(s), the forward solution matrix A (size 3*ndip x nch) is computed, column-normalized, and decomposed via SVD: A = U * diag(sing) * V^T. The members uu, vv, and sing store the SVD factors used for fast goodness-of-fit evaluation and dipole moment reconstruction.

src/examples/ex_inv_dipole_fit/main.cpp
// MEG channels and SSP projectors from the sample file, sphere at (0, 0, 40) mm, ad-hoc noise
// (5e-13 T/m gradiometers, 20 fT magnetometers).
Vector3f r0(0.0f, 0.0f, 0.04f);
std::unique_ptr<InvDipoleFitData> fitData(InvDipoleFitData::setup_dipole_fit_data(
    QString(), sampleAve, QString(), &r0, nullptr, false, QString(), QString(),
    5e-13f, 20e-15f, 0.2e-6f, 0.1f, 0.1f, 0.1f, false, {sampleAve}, true, false));
MatrixXf gain(fitData->nmeg, 3);
const bool fieldOk = InvDipoleFitData::compute_dipole_field(*fitData, truePos, false, gain) == 0; // projected, not whitened
VectorXf field = gain * trueMoment;

InvGuessData guesses(QString(), QString(), 0.0f, 0.02f, 0.015f, fitData.get(), 0.08f); // 15 mm grid in an 80 mm sphere
std::unique_ptr<InvDipoleForward> atTruth(InvDipoleFitData::dipole_forward_one(fitData.get(), truePos, nullptr));
InvEcd dipole;
VectorXf b = field; // fit_one projects and whitens in place
const bool fitted = InvDipoleFitData::fit_one(fitData.get(), &guesses, 0.0f, b, false, dipole);

Public Methods​

InvDipoleForward()​

Constructs a default (empty) InvDipoleForward.

~InvDipoleForward()​

Destructs the InvDipoleForward.

Eigen members are cleaned up automatically.

Example​

Used in examples​

ex_inv_dipole_fit​

Inverse library: equivalent current dipole fitting in a sphere model.

src/examples/ex_inv_dipole_fit/main.cpp, line 106
InvGuessData guesses(QString(), QString(), 0.0f, 0.02f, 0.015f, fitData.get(), 0.08f); // 15 mm grid in an 80 mm sphere
std::unique_ptr<InvDipoleForward> atTruth(InvDipoleFitData::dipole_forward_one(fitData.get(), truePos, nullptr));
InvEcd dipole;
VectorXf b = field; // fit_one projects and whitens in place
const bool fitted = InvDipoleFitData::fit_one(fitData.get(), &guesses, 0.0f, b, false, dipole);
ok &= expect(fieldOk && fitted && fitData->nmeg == 305 && guesses.nguess == 627 && atTruth && atTruth->sing.size() == 3 && dipole.valid && (dipole.rd - truePos).norm() < 1e-3f && (1e9 * dipole.Q.cast<double>() - mneMomentNAm).norm() < 0.02 * mneMomentNAm.norm() && dipole.good > 0.9999f,
             "InvDipoleFitData/InvGuessData/InvDipoleForward/InvEcd: one sample fits the dipole like mne.fit_dipole");

Authors of this file​