%-------------------------------------------------------------------------------
% UF Sparse Matrix Collection, Tim Davis
% http://www.cise.ufl.edu/research/sparse/matrices/Szczerba/Ill_Stokes
% name: Szczerba/Ill_Stokes
% [Ill-conditioned matrix from a Stokes problem, by Dominick Szczerba]
% id: 1862
% date: 2007
% author: D. Szczerba
% ed: T. Davis
% fields: name title A id date author ed kind b notes
% kind: computational fluid dynamics problem
%-------------------------------------------------------------------------------
% notes:
% The matrix comes from a global formulation of the Stokes problem posed  
% directly (without pressure correction) on an unstructured tet mesh.  It 
% includes momentum equations (3 quadrants) and continuity equation (last 
% quadrant).  Unknowns are organized as : vx, vy, vz, p. The last quadrant
% does not contain diagonal entries of course (continuity eq. does not    
% contain pressure) and is the reason bicgstab and related methods do not 
% work.  Does not invert nicely with umfpack (strong oscillations in the  
% 4th quadrant of the solution). LSQR produces better results (smaller    
% oscillations) but takes ages. Dominik Szczerba, Ph.D. Computer Vision   
% Lab, ETH. CH-8092 Zurich. http://www.vision.ee.ethz.ch/~domi            
%-------------------------------------------------------------------------------
