Matrix properties
number of rows	66
number of columns	131
nonzeros	246
structural full rank?	yes
structural rank	66
# of blocks from dmperm	1
# strongly connected comp.	1
explicit zero entries	0
nonzero pattern symmetry	0%
numeric value symmetry	0%
type	real
structure	rectangular
Cholesky candidate?	no
positive definite?	no

author	H. Greenberg
editor	J. Chinneck
date	1993
kind	linear programming problem
2D/3D problem?	no

Additional fields	size and type
b	full 66-by-1
c	full 131-by-1
lo	full 131-by-1
hi	full 131-by-1
z0	full 1-by-1

Notes:

An infeasible Netlib LP problem, in lp/infeas.  For more information        
send email to netlib@ornl.gov with the message:                             
                                                                            
	send index from lp                                                         
	send readme from lp/infeas                                                 
                                                                            
The lp/infeas directory contains infeasible linear programming test problems
collected by John W. Chinneck, Carleton Univ, Ontario Canada.  The following
are relevant excerpts from lp/infeas/readme (by John W. Chinneck):          
                                                                            
In the following, IIS stands for Irreducible Infeasible Subsystem, a set    
of constraints which is itself infeasible, but becomes feasible when any    
one member is removed.  Isolating an IIS from within the larger set of      
constraints defining the model is one analysis approach.                    
                                                                            
PROBLEM DESCRIPTION                                                         
-------------------                                                         
                                                                            
FOREST6, WOODINFE:  very small problems derived from network-based          
forestry models.  The IIS in FOREST6 includes most of the rows.             
WOODINFE is the example problem discussed in detail in Greenberg [1993],    
and has a very small IIS.  Contributor:  H.J.  Greenberg, University of     
Colorado at Denver.                                                         
                                                                            
Name       Rows   Cols   Nonzeros Bounds      Notes                         
forest6      67     95      270   B                                         
                                                                            
                                                                            
REFERENCES                                                                  
----------                                                                  
                                                                            
H.J.  Greenberg (1993).  "A Computer-Assisted Analysis System for           
Mathematical Programming Models and Solutions:  A User's Guide for          
ANALYZE", Kluwer Academic Publishers, Boston.                               
                                                                            

Ordering statistics:	result
nnz(V) for QR, upper bound nnz(L) for LU, with COLAMD	816
nnz(R) for QR, upper bound nnz(U) for LU, with COLAMD	240

SVD-based statistics:
norm(A)	2.67148
min(svd(A))	0.867027
cond(A)	3.08119
rank(A)	66
sprank(A)-rank(A)	0
null space dimension	0
full numerical rank?	yes

singular values (MAT file):	click here
SVD method used:	s = svd (full (A)) ;
status:	ok

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.