• 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/pwt
  • Description: PWT: Nasa matrix, but with a diagonal added to the original matrix
  • download as a MATLAB mat-file, file size: 316 KB. Use SJget(461) or SJget('Nasa/pwt') in MATLAB.
  • download in Matrix Market format, file size: 373 KB.
  • download in Rutherford/Boeing format, file size: 321 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 35473 to 35478 and associated error bounds.


    dmperm of Nasa/pwt

    Matrix properties (click for a legend)  
    number of rows36,519
    number of columns36,519
    structural full rank?yes
    structural rank36,519
    numerical rank 35,475
    dimension of the numerical null space1,044
    numerical rank / min(size(A))0.97141
    Euclidean norm of A 9.9053
    calculated singular value # 354754.5225e-005
    numerical rank defined using a tolerance
    max(size(A))*eps(norm(A)) =
    calculated singular value # 354765.2138e-014
    gap in the singular values at the numerical rank:
    singular value # 35475 / singular value # 35476
    calculated condition number-2
    # of blocks from dmperm57
    # strongly connected comp.57
    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


    Nasa/pwt, GHS_psdef/pwt and Pothen/pwt are identical; Pothen/ has xyz coord.

    Ordering statistics:AMD METIS DMPERM+
    nnz(chol(P*(A+A'+s*I)*P'))1,555,833 1,373,586 1,384,171
    Cholesky flop count1.6e+008 1.1e+008 1.1e+008
    nnz(L+U), no partial pivoting3,075,147 2,710,653 2,731,823
    nnz(V) for QR, upper bound nnz(L) for LU2,667,503 2,280,757 2,306,405
    nnz(R) for QR, upper bound nnz(U) for LU5,000,519 4,300,180 4,338,203

    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.