HB/west0479 sparse matrix

Matrix: HB/west0479

Description: U 8 STAGE COLUMN SECTION, ALL SECTIONS RIGOROUS ( CHEM. ENG. )

download as a MATLAB mat-file, file size: 13 KB. Use UFget(267) or UFget('HB/west0479') in MATLAB.

This matrix is featured in Horror Matrices and other Mathematical Poetry. It also appears as a sample sparse matrix in MATLAB

The Jabberwock, by Sir
John Tenniel (1820-1914). west0479, a well-behaved matrix for direct methods, but according
to John Gilbert, a horror matrix for iterative methods. Try "load west0479"
in MATLAB. It comes from a chemical engineering application, but doesn't
it look like it has claws? And a spiky tail? (image created by cspy).

DMPERM, or finding the strongly-connected components, slices off the creature's head:

dmperm of HB/west0479

scc of HB/west0479

Matrix properties

number of rows 479

number of columns 479

nonzeros 1,888

structural full rank? yes

structural rank 479

# of blocks from dmperm 166

# strongly connected comp. 2

entries not in dmperm blocks 468

explicit zero entries 22

nonzero pattern symmetry 1%

numeric value symmetry 0%

type real

structure unsymmetric

Cholesky candidate? no

positive definite? no

author A. Westerberg
editor I. Duff, R. Grimes, J. Lewis
date 1983
kind chemical process simulation problem
2D/3D problem? no

Ordering statistics: AMD METIS DMPERM+

nnz(chol(P*(A+A'+s*I)*P')) 14,819 18,480 2,821

Cholesky flop count 1.1e+06 1.6e+06 3.6e+04

nnz(L+U), no partial pivoting 29,159 36,481 5,631

nnz(V) for QR, upper bound nnz(L) for LU 3,921 3,681 2,444

nnz(R) for QR, upper bound nnz(U) for LU 7,539 9,053 5,166

Note that all matrix statistics (except nonzero pattern symmetry) exclude the 22 explicit zero entries.

Maintained by Tim Davis, last updated 04-May-2008.
Matrix pictures by cspy, a MATLAB function in the CSparse package.
Matrix graphs by Yifan Hu, AT&T Labs Visualization Group.


The Jabberwock, by Sir John Tenniel (1820-1914).	west0479, a well-behaved matrix for direct methods, but according to John Gilbert, a horror matrix for iterative methods. Try "load west0479" in MATLAB. It comes from a chemical engineering application, but doesn't it look like it has claws? And a spiky tail? (image created by cspy).

Matrix properties
number of rows	479
number of columns	479
nonzeros	1,888
structural full rank?	yes
structural rank	479
# of blocks from dmperm	166
# strongly connected comp.	2
entries not in dmperm blocks	468
explicit zero entries	22
nonzero pattern symmetry	1%
numeric value symmetry	0%
type	real
structure	unsymmetric
Cholesky candidate?	no
positive definite?	no

author	A. Westerberg
editor	I. Duff, R. Grimes, J. Lewis
date	1983
kind	chemical process simulation problem
2D/3D problem?	no

Ordering statistics:	AMD	METIS	DMPERM+
nnz(chol(P(A+A'+sI)*P'))	14,819	18,480	2,821
Cholesky flop count	1.1e+06	1.6e+06	3.6e+04
nnz(L+U), no partial pivoting	29,159	36,481	5,631
nnz(V) for QR, upper bound nnz(L) for LU	3,921	3,681	2,444
nnz(R) for QR, upper bound nnz(U) for LU	7,539	9,053	5,166