Matrix: MathWorks/TS

Description: x=A\b triggers a bug in MATLAB R2009a and earlier

MathWorks/TS graph MathWorks/TS graph
(bipartite graph drawing) (graph drawing of A+A')

MathWorks/TS dmperm of MathWorks/TS
scc of MathWorks/TS

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  • Matrix group: MathWorks
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  • download as a MATLAB mat-file, file size: 108 KB. Use UFget(2256) or UFget('MathWorks/TS') in MATLAB.
  • download in Matrix Market format, file size: 218 KB.
  • download in Rutherford/Boeing format, file size: 93 KB.

    Matrix properties
    number of rows2,142
    number of columns2,142
    structural full rank?no
    structural rank2,140
    # of blocks from dmperm92
    # strongly connected comp.183
    explicit zero entries0
    nonzero pattern symmetry 95%
    numeric value symmetry 4%
    Cholesky candidate?no
    positive definite?no

    authorP. Quillen
    editorT. Davis
    kindcounter-example problem
    2D/3D problem?no

    Additional fieldssize and type
    bsparse 2142-by-1


    This is a structurally singular matrix that triggers a bug in the   
    2-by-2 pivoting strategy in UMFPACK versions 4.1 through 5.3.       
    The bug thus exists in MATLAB R2006b through R2009a.  It was        
    fixed in UMFPACK 5.4 and MATLAB R2009b.  Contributed by Pat Quillen,
    The MathWorks, Inc.  The sprank(A) and rank(A) are 2140.            

    Ordering statistics:result
    nnz(chol(P*(A+A'+s*I)*P')) with AMD73,792
    Cholesky flop count2.8e+06
    nnz(L+U), no partial pivoting, with AMD145,442
    nnz(V) for QR, upper bound nnz(L) for LU, with COLAMD43,575
    nnz(R) for QR, upper bound nnz(U) for LU, with COLAMD86,695

    SVD-based statistics:
    null space dimension2
    full numerical rank?no
    singular value gap2.05462e+13

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

    MathWorks/TS 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.