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

2colamd
Purpose Column approximate minimum degree permutation
Syntax p = colamd(S)
p = colamd(S,knobs)
[p,stats] = colamd(S)
[p,stats] = colamd(S,knobs)
colamd
Description p = colamd(S) returns the column approximate minimum degree
permutation vector for the sparse matrix S. For a non-symmetric matrix S,
S(:,p) tends to have sparser LU factors than S. The Cholesky factorization of
S(:,p)' * S(:,p) also tends to be sparser than that of S'*S.
knobs is a two-element vector. If S is m-by-n, then rows with more than
(knobs(1))*n entries are ignored. Columns with more than (knobs(2))*m
entries are removed prior to ordering, and ordered last in the output
permutation p. If the knobs parameter is not present, then
knobs(1) = knobs(2) = spparms('wh_frac').
stats is an optional vector that provides data about the ordering and the
validity of the matrix S.
stats(1) Number of dense or empty rows ignored by colamd
stats(2) Number of dense or empty columns ignored by colamd
stats(3) Number of garbage collections performed on the internal data
structure used by colamd (roughly of size
2.2*nnz(S) + 4*m + 7*n integers)
stats(4) 0 if the matrix is valid, or 1 if invalid
stats(5) Rightmost column index that is unsorted or contains duplicate
entries, or 0 if no such column exists
stats(6) Last seen duplicate or out-of-order row index in the column
index given by stats(5), or 0 if no such row index exists
stats(7) Number of duplicate and out-of-order row indices
Although, MATLAB built-in functions generate valid sparse matrices, a user
may construct an invalid sparse matrix using the MATLAB C or Fortran APIs
and pass it to colamd. For this reason, colamd verifies that S is valid:
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