Koutsovasilis/F2
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

Notes 
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 fillin).
