Matrix: Koutsovasilis/F2

Description: AUDI engine piston rod; Panos Koutsovasilis, Technische Univ. Dresden

Koutsovasilis/F2 graph
(undirected graph drawing)


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  • download as a MATLAB mat-file, file size: 37 MB. Use UFget(1861) or UFget('Koutsovasilis/F2') in MATLAB.
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    Matrix properties
    number of rows71,505
    number of columns71,505
    structural full rank?yes
    structural rank71,505
    # of blocks from dmperm1
    # strongly connected comp.1
    explicit zero entries0
    nonzero pattern symmetrysymmetric
    numeric value symmetrysymmetric
    Cholesky candidate?yes
    positive definite?no

    authorP. Koutsovasilis
    editorT. Davis
    kindstructural problem
    2D/3D problem?yes


    Stiffness matrix from an AUDI engine piston rod.  This matrix is an ill-     
    condition symmetric indefinite matrix.  In MATLAB 7.4, the matrix is         
    factorized three times in x=A\b.  Inside backslash, CHOLMOD is tried first   
    since the matrix is symmetric and all diagonal entries are positive.  CHOLMOD
    fails since the matrix is indefinite.  Next, UMFPACK is used with default    
    pivot tolerances which maintain sparsity at the (rare) expense of a slight   
    decrease in accuracy.  This succeeds, but the result is flagged as           
    potentially inaccurate because the condition estimate is high.  UMFPACK is   
    then used again with more conservative tolerances (but more fill-in).        

    Ordering statistics:result
    nnz(chol(P*(A+A'+s*I)*P')) with AMD20,756,208
    Cholesky flop count1.2e+10
    nnz(L+U), no partial pivoting, with AMD41,440,911
    nnz(V) for QR, upper bound nnz(L) for LU, with COLAMD40,210,857
    nnz(R) for QR, upper bound nnz(U) for LU, with COLAMD109,796,898

    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.