Matrix properties
number of rows	999,999
number of columns	999,999
nonzeros	4,995,991
structural full rank?	yes
structural rank	999,999
# 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?	yes

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/ecology2 matrix comes from 
a 2D, 1000-by-1000 mesh (5 pt stencil).  It is a symmetric positive 
definite 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	45,752,523
Cholesky flop count	2.0e+10
nnz(L+U), no partial pivoting, with AMD	90,505,047
nnz(V) for QR, upper bound nnz(L) for LU, with COLAMD	69,455,113
nnz(R) for QR, upper bound nnz(U) for LU, with COLAMD	128,056,728

Maintained by Tim Davis, last updated 01-Apr-2011.
Matrix pictures by cspy, a MATLAB function in the CSparse package.
Matrix graphs by Yifan Hu, AT&T Labs Visualization Group.