denormals in A+alpha*I as alpha > 0 varies, J. Castrillon, Teledyne
Name denormal
Group Castrillon
Matrix ID 1892
Num Rows 89,400
Num Cols 89,400
Nonzeros 1,156,224
Pattern Entries 1,156,224
Kind Counter Example Problem
Symmetric Yes
Date 2008
Author J. Castrillon
Editor T. Davis
Structural Rank 89,400
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 yes
Type real
Download MATLAB Rutherford Boeing Matrix Market
The problem is x=(A+alpha*I)\b as alpha varies from 0 to 100.  However,
as this occurs, performance suffers because of the many denormals that 
appear below the diagonal in L.