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

  • Matrix: Gset/G50
  • Description: 2D torus, 120-by-25
  • download as a MATLAB mat-file, file size: 31 KB. Use SJget(8) or SJget('Gset/G50') in MATLAB.
  • download in Matrix Market format, file size: 23 KB.
  • download in Rutherford/Boeing format, file size: 20 KB.


    Routine svd from Matlab (R2008a) used to calculate the singular values.


    Matrix properties (click for a legend)  
    number of rows3,000
    number of columns3,000
    structural full rank?yes
    structural rank3,000
    numerical rank 2,991
    dimension of the numerical null space9
    numerical rank / min(size(A))0.997
    Euclidean norm of A 4
    calculated singular value # 29910.0027409
    numerical rank defined using a tolerance
    max(size(A))*eps(norm(A)) =
    calculated singular value # 29927.1351e-016
    gap in the singular values at the numerical rank:
    singular value # 2991 / singular value # 2992
    calculated condition number1.0278e+017
    # 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?unknown

    authorC. Helmberg
    editorY. Ye
    kindundirected random graph
    2D/3D problem?no

    Ordering statistics:AMD METIS
    nnz(chol(P*(A+A'+s*I)*P'))58,007 54,595
    Cholesky flop count2.5e+006 2.0e+006
    nnz(L+U), no partial pivoting113,014 106,190
    nnz(V) for QR, upper bound nnz(L) for LU75,753 64,878
    nnz(R) for QR, upper bound nnz(U) for LU135,072 117,663

    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.