• UF Sparse Matrix Collection
  • Matrix group: LPnetlib
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  • Matrix: LPnetlib/lpi_itest2
  • Description: Netlib LP problem itest2: minimize c'*x, where Ax=b, lo<=x<=hi
  • download as a MATLAB mat-file, file size: 2 KB. Use UFget(719) or UFget('LPnetlib/lpi_itest2') in MATLAB.
  • download in Matrix Market format
  • download in Rutherford/Boeing format

    LPnetlib/lpi_itest2

    Matrix properties
    number of rows9
    number of columns13
    nonzeros26
    structural full rank?yes
    structural rank9
    # of blocks from dmperm1
    # strongly connected comp.1
    entries not in dmperm blocks0
    explicit zero entries0
    nonzero pattern symmetry 0%
    numeric value symmetry 0%
    typereal
    structurerectangular
    Cholesky candidate?no
    positive definite?no

    authorJ. Chinneck, E. Dravnieks
    editorJ. Chinneck
    date1991
    kindlinear programming problem
    2D/3D problem?no

    Additional fieldssize and type
    bfull 9-by-1
    cfull 13-by-1
    lofull 13-by-1
    hifull 13-by-1
    z0full 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                                                         
-------------------                                                         
                                                                            
ITEST6, ITEST2:  very small problems having numerous clustered IISs.        
These match problems 1 and 2, respectively, in Chinneck and Dravnieks       
[1991].  Contributors:  J.W.  Chinneck and E.W.  Dravnieks, Carleton        
University.                                                                 
                                                                            
Name       Rows   Cols   Nonzeros Bounds      Notes                         
itest2       10      4       17                                             
                                                                            
REFERENCES                                                                  
----------                                                                  
                                                                            
J.W.  Chinneck and E.W.  Dravnieks (1991).  "Locating Minimal Infeasible    
Constraint Sets in Linear Programs", ORSA Journal on Computing, Volume      
3, No. 2.

    Ordering statistics:AMD METIS
    nnz(V) for QR, upper bound nnz(L) for LU36 31
    nnz(R) for QR, upper bound nnz(U) for LU32 32

    Maintained by Tim Davis, last updated 05-Mar-2008.
    Matrix pictures by cspy, a MATLAB function in the CSparse package.