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

  • Matrix: Nasa/skirt
  • Description: SKIRT: Nasa matrix, but with a diagonal added to the original matrix
  • download as a MATLAB mat-file, file size: 191 KB. Use SJget(395) or SJget('Nasa/skirt') in MATLAB.
  • download in Matrix Market format, file size: 223 KB.
  • download in Rutherford/Boeing format, file size: 148 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 9829 to 9834 and associated error bounds.


    dmperm of Nasa/skirt

    Matrix properties (click for a legend)  
    number of rows12,598
    number of columns12,598
    structural full rank?yes
    structural rank12,598
    numerical rank 9,831
    dimension of the numerical null space2,767
    numerical rank / min(size(A))0.78036
    Euclidean norm of A 23.314
    calculated singular value # 98314.6429e-005
    numerical rank defined using a tolerance
    max(size(A))*eps(norm(A)) =
    calculated singular value # 98322.1958e-014
    gap in the singular values at the numerical rank:
    singular value # 9831 / singular value # 9832
    calculated condition number-2
    # of blocks from dmperm7
    # strongly connected comp.7
    entries not in dmperm blocks0
    explicit zero entries0
    nonzero pattern symmetrysymmetric
    numeric value symmetrysymmetric
    Cholesky candidate?yes
    positive definite?no

    editorG. Kumfert, A. Pothen
    kindduplicate structural problem
    2D/3D problem?yes


    Identical to Pothen/skirt; the latter has xyz coordinates.

    Ordering statistics:AMD METIS DMPERM+
    nnz(chol(P*(A+A'+s*I)*P'))480,579 484,160 473,042
    Cholesky flop count3.4e+007 3.1e+007 3.0e+007
    nnz(L+U), no partial pivoting948,560 955,722 933,486
    nnz(V) for QR, upper bound nnz(L) for LU826,916 671,752 706,950
    nnz(R) for QR, upper bound nnz(U) for LU1,528,684 1,259,102 1,258,677

    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.