AUDI engine piston rod; Panos Koutsovasilis, Technische Univ. Dresden
Name F2
Group Koutsovasilis
Matrix ID 1861
Num Rows 71,505
Num Cols 71,505
Nonzeros 5,294,285
Pattern Entries 5,294,285
Kind Structural Problem
Symmetric Yes
Date 2007
Author P. Koutsovasilis
Editor T. Davis
Structural Rank 71,505
Structural Rank Full true
Num Dmperm Blocks 1
Strongly Connect Components 1
Num Explicit Zeros 0
Pattern Symmetry 100%
Numeric Symmetry 100%
Cholesky Candidate yes
Positive Definite no
Type real
Download MATLAB Rutherford Boeing Matrix Market
Stiffness matrix from an AUDI engine piston rod.  This matrix is an ill-     
condition symmetric indefinite matrix.  In MATLAB 7.4, the matrix is         
factorized three times in x=A\b.  Inside backslash, CHOLMOD is tried first   
since the matrix is symmetric and all diagonal entries are positive.  CHOLMOD
fails since the matrix is indefinite.  Next, UMFPACK is used with default    
pivot tolerances which maintain sparsity at the (rare) expense of a slight   
decrease in accuracy.  This succeeds, but the result is flagged as           
potentially inaccurate because the condition estimate is high.  UMFPACK is   
then used again with more conservative tolerances (but more fill-in).