Matrix: GHS_psdef/wathen120

Description: Gould,Higham,Scott: matrix from Andy Wathen, Oxford Univ.

GHS_psdef/wathen120 graph
(undirected graph drawing)


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  • Matrix group: GHS_psdef
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  • download as a MATLAB mat-file, file size: 2 MB. Use UFget(1289) or UFget('GHS_psdef/wathen120') in MATLAB.
  • download in Matrix Market format, file size: 3 MB.
  • download in Rutherford/Boeing format, file size: 2 MB.

    Matrix properties
    number of rows36,441
    number of columns36,441
    structural full rank?yes
    structural rank36,441
    # of blocks from dmperm1
    # strongly connected comp.1
    explicit zero entries0
    nonzero pattern symmetrysymmetric
    numeric value symmetrysymmetric
    Cholesky candidate?yes
    positive definite?yes

    authorA. Wathen
    editorN. Gould, Y. Hu, J. Scott
    kindrandom 2D/3D problem
    2D/3D problem?yes


    A = gallery('wathen',100,120) ; % (in MATLAB)                   
    To initialize the MATLAB random number generator to replicate   
    this matrix, first do the following:                            
    rand('state',0); A = gallery('wathen',100,100)                  
    and then generate this matrix using the 100,120 arguments above.

    Ordering statistics:result
    nnz(chol(P*(A+A'+s*I)*P')) with AMD1,845,324
    Cholesky flop count2.5e+08
    nnz(L+U), no partial pivoting, with AMD3,654,207
    nnz(V) for QR, upper bound nnz(L) for LU, with COLAMD3,750,470
    nnz(R) for QR, upper bound nnz(U) for LU, with COLAMD8,902,766

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

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

    GHS_psdef/wathen120 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.