Dehghani/light_in_tissue

Light transport in soft tissue. Hamid Dehghani, Univ. Exeter, UK
Name light_in_tissue
Group Dehghani
Matrix ID 1873
Num Rows 29,282
Num Cols 29,282
Nonzeros 406,084
Pattern Entries 406,084
Kind Electromagnetics Problem
Symmetric No
Date 2007
Author H. Dehghani
Editor T. Davis
Structural Rank 29,282
Structural Rank Full true
Num Dmperm Blocks 1
Strongly Connect Components 1
Num Explicit Zeros 0
Pattern Symmetry 100%
Numeric Symmetry 0%
Cholesky Candidate no
Positive Definite no
Type complex
SVD Statistics
Matrix Norm 2.663552e+00
Minimum Singular Value 3.405251e-04
Condition Number 7.821896e+03
Rank 29,282
sprank(A)-rank(A) 0
Null Space Dimension 0
Full Numerical Rank? yes
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Notes
% The problem is solving the fluence (PHI) of light in soft tissue using
% a simplified 3rd spherical harmonic expansion (SPN3) of the Radiative 
% Transport Equation.  There are two coupled equations to solve:        
% M1*phi1 = Q + (M2*phi2)                                   eq(1)       
% (M4 - (M3*inv(M1)*M2))*phi2 = -2/3*Q + M3*inv(M1)*Q       eq(2)       
% PHI = phi1 - (1/3).*phi2                                  eq(3)       
                                                                        
Problem = UFget ('Dehghani/light_in_tissue') ;                          
A = Problem.A ;                   % get the problem                     
Q = Problem.aux.Q ;                                                     
k = size (A,1) / 2 ;                                                    
M1 = A (1:k,1:k) ;                                                      
M2 = A (1:k,k+1:end) ;                                                  
M3 = A (k+1:end, 1:k) ;                                                 
M4 = A (k+1:end, k+1:end) ;                                             
elements = Problem.aux.elements ;                                       
nodes = Problem.aux.nodes ;                                             
                                                                        
Q2 = (-(2/3).*Q) + (M3*(M1\Q)) ;  % create rhs for equation 2           
Q2 = [sparse(k,1) ; Q2] ;                                               
phi2 = A\Q2 ;                     % solve for phi2                      
phi2 = phi2 (end/2+1:end,:) ;                                           
Q1 = Q + M2*phi2 ;                % calculate rhs for equation 1        
phi1 = M1\Q1;                     % solve for phi1                      
PHI = phi1 - (1/3).*phi2;                                               
figure (1) ; clf                  % plot results                        
trisurf(elements, nodes(:,1), nodes(:,2), nodes(:,3), log(abs(PHI))) ;  
shading interp ;                                                        
view (2) ;                                                              
colorbar('horiz') ;                                                     
axis equal ;                                                            
axis off ;                                                              
colormap hot ;