MATLAB Function Reference Volume 1: A - E - Bad Request

colamd
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• If a row index appears two or more times in the same column, colamd ignores
the duplicate entries, continues processing, and provides information about
the duplicate entries in stats(4:7).
• If row indices in a column are out of order, colamd sorts each column of its
internal copy of the matrix S (but does not repair the input matrix S),
continues processing, and provides information about the out-of-order
entries in stats(4:7).
• If S is invalid in any other way, colamd cannot continue. It prints an error
message, and returns no output arguments (p or stats) .
The ordering is followed by a column elimination tree post-ordering.
Note colamd tends to be faster than colmmd and tends to return a better
ordering.
See Also colmmd, colperm, spparms, symamd, symmmd, symrcm
References [1] The authors of the code for colamd are Stefan I. Larimore and Timothy A.
Davis (davis@cise.ufl.edu), University of Florida. The algorithm was
developed in collaboration with John Gilbert, Xerox PARC, and Esmond Ng,
Oak Ridge National Laboratory. Sparse Matrix Algorithms Research at the
University of Florida: http://www.cise.ufl.edu/research/sparse/