• SJSU Singular Matrix Database
  • Matrix group: GHS_psdef
  • Click here for a description of the GHS_psdef group.
  • Click here for a list of all matrices
  • Click here for a list of all matrix groups

  • Matrix: GHS_psdef/ford1
  • Description: Gould, Hu, & Scott: car surface mesh, from Pothen & Kumfert
  • download as a MATLAB mat-file, file size: 168 KB. Use SJget(383) or SJget('GHS_psdef/ford1') in MATLAB.
  • download in Matrix Market format, file size: 156 KB.
  • download in Rutherford/Boeing format, file size: 147 KB.


    A singular value of A is guaranteed1 to be in the interval pictured by the blue bars around each of the calculated singular values.

    Routine svds_err, version 1.0, used with Matlab (R2008a) to calculate the 6 largest singular values and associated error bounds.
    Routine spnrank, version 1.0, used with Matlab (R2008a) to calculate singular values 18192 to 18197 and associated error bounds.


    Matrix properties (click for a legend)  
    number of rows18,728
    number of columns18,728
    structural full rank?yes
    structural rank18,728
    numerical rank 18,194
    dimension of the numerical null space534
    numerical rank / min(size(A))0.97149
    Euclidean norm of A 13.971
    calculated singular value # 181946.8712e-005
    numerical rank defined using a tolerance
    max(size(A))*eps(norm(A)) =
    calculated singular value # 181951.4803e-016
    gap in the singular values at the numerical rank:
    singular value # 18194 / singular value # 18195
    calculated condition number-2
    # of blocks from dmperm1
    # strongly connected comp.1
    entries not in dmperm blocks0
    explicit zero entries0
    nonzero pattern symmetrysymmetric
    numeric value symmetrysymmetric
    Cholesky candidate?yes
    positive definite?no

    authorG. Kumfert, A. Pothen
    editorN. Gould, Y. Hu, J. Scott
    kindstructural problem
    2D/3D problem?yes

    Ordering statistics:AMD METIS
    nnz(chol(P*(A+A'+s*I)*P'))303,615 323,725
    Cholesky flop count1.4e+007 1.5e+007
    nnz(L+U), no partial pivoting588,502 628,722
    nnz(V) for QR, upper bound nnz(L) for LU652,845 609,974
    nnz(R) for QR, upper bound nnz(U) for LU1,237,976 1,160,459

    Maintained by Leslie Foster, last updated 24-Apr-2009.

    Entries 5 through 14 in the table of matrix properties and the singular
    value plot were created using SJsingular code. The other plots
    and statistics are produced using utilities from the SuiteSparse package.
    Matrix color plot pictures by cspy, a MATLAB function in the CSparse package.