Matrix properties
number of rows	1,000,000
number of columns	1,000,000
nonzeros	4,996,000
structural full rank?	yes
structural rank	1,000,000
# of blocks from dmperm	1
# strongly connected comp.	1
entries not in dmperm blocks	0
explicit zero entries	0
nonzero pattern symmetry	symmetric
numeric value symmetry	symmetric
type	real
structure	symmetric
Cholesky candidate?	yes
positive definite?	no

author	B. McRae
editor	T. Davis
date	2008
kind	2D/3D problem
2D/3D problem?	yes

Notes:

Landscape ecology problem, using electrical network theory to model 
animal movement an gene flow.  The McRae/ecology1 matrix comes from 
a 2D, 1000-by-1000 mesh (5 pt stencil).  It is an ill-conditioned   
symmetric indefinite matrix.  Source: Brad McRae, National Center   
for Ecological Analysis and Synthesis Santa Barbara, CA.            

Ordering statistics:	AMD	METIS
nnz(chol(P*(A+A'+s*I)*P'))	44,674,783	37,736,412
Cholesky flop count	1.8e+10	1.6e+10
nnz(L+U), no partial pivoting	88,349,566	74,472,824
nnz(V) for QR, upper bound nnz(L) for LU	74,067,950	70,670,443
nnz(R) for QR, upper bound nnz(U) for LU	135,597,872	129,966,094

Maintained by Tim Davis, last updated 07-May-2008.
Matrix pictures by cspy, a MATLAB function in the CSparse package.
Matrix graphs by Yifan Hu, AT&T Labs Visualization Group.