Matrix: McRae/ecology2

Description: circuitscape: circuit theory applied to animal/gene flow. B. McRae, UCSB

McRae/ecology2 graph
(undirected graph drawing)


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  • download as a MATLAB mat-file, file size: 8 MB. Use UFget(1883) or UFget('McRae/ecology2') in MATLAB.
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    Matrix properties
    number of rows999,999
    number of columns999,999
    structural full rank?yes
    structural rank999,999
    # of blocks from dmperm1
    # strongly connected comp.1
    explicit zero entries0
    nonzero pattern symmetrysymmetric
    numeric value symmetrysymmetric
    Cholesky candidate?yes
    positive definite?yes

    authorB. McRae
    editorT. Davis
    kind2D/3D problem
    2D/3D problem?yes


    Landscape ecology problem, using electrical network theory to model 
    animal movement an gene flow.  The McRae/ecology2 matrix comes from 
    a 2D, 1000-by-1000 mesh (5 pt stencil).  It is a symmetric positive 
    definite matrix.  Source: Brad McRae, National Center for Ecological
    Analysis and Synthesis Santa Barbara, CA.                           

    Ordering statistics:result
    nnz(chol(P*(A+A'+s*I)*P')) with AMD45,752,523
    Cholesky flop count2.0e+10
    nnz(L+U), no partial pivoting, with AMD90,505,047
    nnz(V) for QR, upper bound nnz(L) for LU, with COLAMD69,455,113
    nnz(R) for QR, upper bound nnz(U) for LU, with COLAMD128,056,728

    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.