Matrix: LPnetlib/lpi_woodinfe

Description: Netlib LP problem woodinfe: minimize c'*x, where Ax=b, lo<=x<=hi

LPnetlib/lpi_woodinfe graph
(bipartite graph drawing)

LPnetlib/lpi_woodinfe dmperm of LPnetlib/lpi_woodinfe
scc of LPnetlib/lpi_woodinfe

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  • Matrix group: LPnetlib
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  • download as a MATLAB mat-file, file size: 2 KB. Use UFget(731) or UFget('LPnetlib/lpi_woodinfe') in MATLAB.
  • download in Matrix Market format, file size: 2 KB.
  • download in Rutherford/Boeing format, file size: 2 KB.

    Matrix properties
    number of rows35
    number of columns89
    structural full rank?yes
    structural rank35
    # of blocks from dmperm3
    # strongly connected comp.6
    explicit zero entries0
    nonzero pattern symmetry 0%
    numeric value symmetry 0%
    Cholesky candidate?no
    positive definite?no

    authorH. Greenberg
    editorJ. Chinneck
    kindlinear programming problem
    2D/3D problem?no

    Additional fieldssize and type
    bfull 35-by-1
    cfull 89-by-1
    lofull 89-by-1
    hifull 89-by-1
    z0full 1-by-1


    An infeasible Netlib LP problem, in lp/infeas.  For more information        
    send email to 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                         
    woodinfe     36     89      209   B                                         
    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 COLAMD284
    nnz(R) for QR, upper bound nnz(U) for LU, with COLAMD102

    SVD-based statistics:
    null space dimension0
    full numerical rank?yes

    singular values (MAT file):click here
    SVD method used:s = svd (full (R)) ; where [~,R,E] = spqr (A') with droptol of zero

    LPnetlib/lpi_woodinfe svd

    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.