Matrix: McRae/ecology1

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

McRae/ecology1 graph
(undirected graph drawing)


  • Home page of the UF Sparse Matrix Collection
  • Matrix group: McRae
  • Click here for a description of the McRae group.
  • Click here for a list of all matrices
  • Click here for a list of all matrix groups
  • download as a MATLAB mat-file, file size: 8 MB. Use UFget(1882) or UFget('McRae/ecology1') in MATLAB.
  • download in Matrix Market format, file size: 9 MB.
  • download in Rutherford/Boeing format, file size: 7 MB.

    Matrix properties
    number of rows1,000,000
    number of columns1,000,000
    structural full rank?yes
    structural rank1,000,000
    # of blocks from dmperm1
    # strongly connected comp.1
    explicit zero entries0
    nonzero pattern symmetrysymmetric
    numeric value symmetrysymmetric
    Cholesky candidate?yes
    positive definite?no

    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/ecology1 matrix comes from 
    a 2D, 1000-by-1000 mesh (5 pt stencil).  It is an ill-conditioned   
    symmetric indefinite 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 AMD44,674,783
    Cholesky flop count1.8e+10
    nnz(L+U), no partial pivoting, with AMD88,349,566
    nnz(V) for QR, upper bound nnz(L) for LU, with COLAMD74,067,950
    nnz(R) for QR, upper bound nnz(U) for LU, with COLAMD135,597,872

    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.