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InvBeamformer

Namespace: INVLIB  ·  Library: Inverse Library

#include <inv/inv_beamformer.h>

class INVLIB::InvBeamformer

Stores pre-computed beamformer spatial filter weights and associated metadata.

For LCMV: weights is a single matrix (n_sources * n_orient, n_channels). For DICS: weights is a vector of matrices, one per frequency bin.

This class is the C++ equivalent of MNE-Python's Beamformer dict.

Computed beamformer spatial filter container.

src/examples/ex_inv_beamformer/main.cpp
FiffCov dataCov = noiseCov; // noise plus the two sources
dataCov.data += g1 * g1.transpose() + g2 * g2.transpose();
const InvBeamformer lcmv = InvLCMV::makeLCMV(info, fwd, dataCov, 0.05, noiseCov,
                                             BeamformerPickOri::MaxPower, BeamformerWeightNorm::UnitNoiseGain);
const VectorXd lcmvPower = InvLCMV::applyLCMVCov(dataCov, lcmv).data.col(0); // one value per source

Public Methods​

InvBeamformer()​

Default constructor — produces an empty (invalid) beamformer.

isValid()​

Returns true if this beamformer contains valid filter weights.

Returns:

  • bool — True if filter weights are present, false for a default-constructed beamformer.

nSources()​

Returns the number of source points.

Returns:

  • int — Number of source points covered by the filter weights.

nChannels()​

Returns the number of channels.

Returns:

  • int — Number of sensor channels the filter weights apply to.

nOrient()​

Returns the number of orientations per source (1 or 3).

Returns:

  • int — 1 for fixed or max-power orientation, 3 for free orientation.

nFreqs()​

Returns the number of frequency bins (1 for LCMV, >= 1 for DICS).

Returns:

  • int — Number of frequency bins with separate filter weights.

Example​

Used in examples​

ex_inv_beamformer​

Inverse library: LCMV and DICS beamformers and the RAP-MUSIC family of dipole scanners.

src/examples/ex_inv_beamformer/main.cpp, line 126
FiffCov dataCov = noiseCov; // noise plus the two sources
dataCov.data += g1 * g1.transpose() + g2 * g2.transpose();
const InvBeamformer lcmv = InvLCMV::makeLCMV(info, fwd, dataCov, 0.05, noiseCov,
                                             BeamformerPickOri::MaxPower, BeamformerWeightNorm::UnitNoiseGain);
const VectorXd lcmvPower = InvLCMV::applyLCMVCov(dataCov, lcmv).data.col(0); // one value per source
// mne.beamformer.make_lcmv(..., pick_ori="max-power", weight_norm="unit-noise-gain") + apply_lcmv_cov:
// sum 117.705, source 10 16.5306, source 50 3.92173
Index lcmvBest = 0;
lcmvPower.maxCoeff(&lcmvBest);
ok &= expect(lcmv.isValid() && lcmvPower.size() == 70 && lcmvBest == 10 && near(lcmvPower.sum(), 117.70495401512653, 1e-5) && near(lcmvPower(10), 16.530644994286707, 1e-5) && near(lcmvPower(50), 3.9217347708280537, 1e-5),
             "InvLCMV/InvBeamformer: max-power LCMV power on V1 matches mne.beamformer.apply_lcmv_cov");

Authors of this file​