3D Transient Electromagnetic Modelleing, Stefan Guettel, Univ Manchester
                                                                        
The TEM problem relates to the time-dependent modelling of a transient  
electromagnetic field in geophysical exploration. The set contains a    
matrix pencil (C,M) and an initial value vector q, corresponding to a   
Nedelec finite element discretization of Maxwell's equations for the    
electric field density e(t). The curl-curl matrix C is symmetric        
positive semi-definite and the mass matrix M is symmetric positive      
definite. The problem to be solved is a linear initial value problem    
                                                                        
   M*e'(t) = C*e(t),  M*e(0) = q,                                       
                                                                        
for logarithmically distributed time points t in the interval           
[1e-6,1e-3].                                                            
                                                                        
There are three test sets which are described in the following          
publication:                                                            
                                                                        
@article{BEG2015,                                                       
  title={Three-dimensional transient electromagnetic modelling using    
    rational {K}rylov methods},                                         
  author={B{\"o}rner, Ralph-Uwe and Ernst, Oliver G and G{\"u}ttel,     
    Stefan},                                                            
  journal={Geophysical Journal International},                          
  volume={202},                                                         
  number={3},                                                           
  pages={2025--2043},                                                   
  year={2015},                                                          
  publisher={Oxford University Press}                                   
}                                                                       
                                                                        
The problem details are                                                 
                                                                        
TEM27623: section 5.1 in the above paper; layered half-space problem    
discretized by 24582 tetrahedral elements of order 1 giving rise to     
27623 degrees of freedom.                                               
                                                                        
TEM152078: section 5.1 in the above paper; layered half-space problem   
discretized by 24582 tetrahedral elements of order 2 giving rise to     
152078 degrees of freedom.                                              
                                                                        
TEM181302: section 5.2 in the above paper; homogeneous subsurface with  
topography discretized by 28849 tetrahedral elements of order 2 giving  
rise to 181302 degrees of freedom.                                      
                                                                        
In the SuiteSparse Matrix Collection, the primary matrix Problem.A is   
the matrix C in the TEM* problems.  The M matrix appears as             
Problem.aux.M, and the q vector is Problem.aux.q.