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
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:	result
nnz(chol(P*(A+A'+s*I)*P')) with AMD	44,674,783
Cholesky flop count	1.8e+10
nnz(L+U), no partial pivoting, with AMD	88,349,566
nnz(V) for QR, upper bound nnz(L) for LU, with COLAMD	74,067,950
nnz(R) for QR, upper bound nnz(U) for LU, with COLAMD	135,597,872

For a description of the statistics displayed above, click here.

Maintained by Tim Davis, last updated 12-Mar-2014.
Matrix pictures by cspy, a MATLAB function in the CSparse package.
Matrix graphs by Yifan Hu, AT&T Labs Visualization Group.