vb_dipole_basis

 Lead field for dipole estimation
  G = vb_dipole_basis(V, xx, pick, Qpick, Wsensor, V0, mode)
 --- INPUT
  V(n,:)  : dipole position (3-D coordinate) at n-th vertex
 xx(n,:)  : dipole current direction (unit vector) at n-th vertex
  pick(k, 1:3) : Sensor coil position  : コイル位置, 
 Qpick(k, 1:3)    : Sensor coil direction : コイル方向

 Wsensor(m,n) = n-th coil weight for m-th sensor channel
   basis(channel,dipole) = Wsensor * basis(coil,dipole)
 --- Optional input
 V0   : Center of spherical model (1 x 3) = [0 0 0] (default)
 mode = 0: Biot-Savart     (default)
      = 1: Sarvas          
      = 2: Magnetic dipole 
      = 3: EEG             
 --- Output
 G : Lead Field (Ndipole, Nsensor)

 2006-12-16 made by M.Sato
 2007-7-9 modified by M.Sato

 Copyright (C) 2011, ATR All Rights Reserved.
 License : New BSD License(see VBMEG_LICENSE.txt)

0001 function    G = vb_dipole_basis(V, xx, pick, Qpick, Wsensor, V0, mode)
0002 % Lead field for dipole estimation
0003 %  G = vb_dipole_basis(V, xx, pick, Qpick, Wsensor, V0, mode)
0004 % --- INPUT
0005 %  V(n,:)  : dipole position (3-D coordinate) at n-th vertex
0006 % xx(n,:)  : dipole current direction (unit vector) at n-th vertex
0007 %  pick(k, 1:3) : Sensor coil position  : コイル位置,
0008 % Qpick(k, 1:3)    : Sensor coil direction : コイル方向
0009 %
0010 % Wsensor(m,n) = n-th coil weight for m-th sensor channel
0011 %   basis(channel,dipole) = Wsensor * basis(coil,dipole)
0012 % --- Optional input
0013 % V0   : Center of spherical model (1 x 3) = [0 0 0] (default)
0014 % mode = 0: Biot-Savart     (default)
0015 %      = 1: Sarvas
0016 %      = 2: Magnetic dipole
0017 %      = 3: EEG
0018 % --- Output
0019 % G : Lead Field (Ndipole, Nsensor)
0020 %
0021 % 2006-12-16 made by M.Sato
0022 % 2007-7-9 modified by M.Sato
0023 %
0024 % Copyright (C) 2011, ATR All Rights Reserved.
0025 % License : New BSD License(see VBMEG_LICENSE.txt)
0026 
0027 if ~exist('V0','var') | isempty(V0), V0 = [0 0 0]; end;
0028 if ~exist('mode','var'), mode = 0; end;
0029 
0030 % Change center of coordinate
0031 pick = [pick(:,1)-V0(1), pick(:,2)-V0(2), pick(:,3)-V0(3)];
0032 V    = [   V(:,1)-V0(1),    V(:,2)-V0(2),    V(:,3)-V0(3)];
0033 
0034 switch mode
0035 case 0
0036     % Magnetic field by Biot-Savart
0037     G = vb_dipole_magnetic(V, xx, pick, Qpick ) * Wsensor'; 
0038 case 1
0039     % Magnetic field by Sarvas
0040     G = vb_sarvas_basis(V, xx, pick, Qpick) * Wsensor';
0041 case 2
0042     % Magnetic field by magnetic dipole
0043     G = vb_dipole_field_magdipole(V, xx, pick, Qpick ) * Wsensor'; 
0044 case 3
0045     % EEG 3-shell Sphere model
0046     R = [ 0.87  0.92   1.0 ];
0047     Rmax  = max(sqrt(sum(V.^2,2)));
0048     Rpick = mean(sqrt(sum(pick.^2,2)));
0049     R     = R * Rpick;
0050     % Conductivity  from innermost to outermost
0051     sigma = [ 0.62 0.03 0.62 ];
0052     
0053     % Electric potential
0054     G = vb_eeg_legendre(V, xx, pick, R, sigma);
0055 end
0056 
0057