Matrix: LPnetlib/lpi_qual

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

LPnetlib/lpi_qual graph
(bipartite graph drawing)

LPnetlib/lpi_qual dmperm of LPnetlib/lpi_qual

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  • Matrix group: LPnetlib
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  • download as a MATLAB mat-file, file size: 9 KB. Use UFget(727) or UFget('LPnetlib/lpi_qual') in MATLAB.
  • download in Matrix Market format, file size: 10 KB.
  • download in Rutherford/Boeing format, file size: 9 KB.

    Matrix properties
    number of rows323
    number of columns464
    structural full rank?yes
    structural rank323
    # of blocks from dmperm13
    # strongly connected comp.1
    explicit zero entries0
    nonzero pattern symmetry 0%
    numeric value symmetry 0%
    Cholesky candidate?no
    positive definite?no

    authorT. Baker
    editorJ. Chinneck
    kindlinear programming problem
    2D/3D problem?no

    Additional fieldssize and type
    bfull 323-by-1
    cfull 464-by-1
    lofull 464-by-1
    hifull 464-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                                                         
    CHEMCOM, QUAL, REFINERY, REACTOR, VOL1:  medium size problems derived       
    from a petrochemical plant model.  Doctored to generate infeasibility       
    due to inability to meet volume or quality restrictions.  With the          
    exception of REACTOR, these are highly volatile problems, yielding IISs     
    of varying sizes when different IIS isolation algorithms are applied.       
    See Chinneck [1993] for further discussion.  Contributor:  Tom Baker,       
    Chesapeake Decision Sciences.                                               
    Name       Rows   Cols   Nonzeros Bounds      Notes                         
    qual        324    464     1714   B    FX                                   
    J.W.  Chinneck (1993).  "Finding the Most Useful Subset of Constraints      
    for Analysis in an Infeasible Linear Program", technical report             
    SCE-93-07, Systems and Computer Engineering, Carleton University,           
    Ottawa, Canada.                                                             

    Ordering statistics:result
    nnz(V) for QR, upper bound nnz(L) for LU, with COLAMD14,310
    nnz(R) for QR, upper bound nnz(U) for LU, with COLAMD5,067

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

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

    LPnetlib/lpi_qual 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.