aa_calc_system_mat

 AA_CALC_SYSTEM_MAT: SS= aa_calc_system_mat( fwd_model, img)
 Calc system matrix for Andy Adler's EIT code
 fwd_model = forward model
 img       = image background for system matrix calc
 s_mat.E = CC' * SS * conductivites * CC;
 where:
   SS  = Unconnected system Matrix
   CC  = Connectivity Matrix

0001 function s_mat= aa_calc_system_mat( fwd_model, img)
0002 % AA_CALC_SYSTEM_MAT: SS= aa_calc_system_mat( fwd_model, img)
0003 % Calc system matrix for Andy Adler's EIT code
0004 % fwd_model = forward model
0005 % img       = image background for system matrix calc
0006 % s_mat.E = CC' * SS * conductivites * CC;
0007 % where:
0008 %   SS  = Unconnected system Matrix
0009 %   CC  = Connectivity Matrix
0010 
0011 % (C) 2005 Andy Adler. License: GPL version 2 or version 3
0012 % $Id: aa_calc_system_mat.html 2819 2011-09-07 16:43:11Z aadler $
0013 
0014 FC= aa_system_mat_fields( fwd_model);
0015 lFC= size(FC,1);
0016 
0017 pp= aa_fwd_parameters( fwd_model);
0018 elem_sigma = kron( img.elem_data(:), ones(pp.n_dims,1) );
0019 
0020 ES= ones(lFC,1);
0021 ES(1:length(elem_sigma))= elem_sigma;
0022 ES= spdiags(ES,0,lFC,lFC);
0023 
0024 s_mat.E= FC' * ES * FC;
0025