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function [p, stats] = ccolamd (S, knobs, cmember) %#ok
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%CCOLAMD constrained column approximate minimum degree permutation.
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% p = CCOLAMD(S) returns the column approximate minimum degree permutation
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% vector for the sparse matrix S. For a non-symmetric matrix S, S(:,p)
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% tends to have sparser LU factors than S. chol(S(:,p)'*S(:,p)) also tends
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% to be sparser than chol(S'*S). p=ccolamd(S,1) optimizes the ordering for
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% lu(S(:,p)). The ordering is followed by a column elimination tree post-
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% p = ccolamd (S,knobs,cmember)
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% knobs is an optional one- to five-element input vector, with a default
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% value of [0 10 10 1 0] if not present or empty ([ ]). Entries not present
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% are set to their defaults.
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% knobs(1): if nonzero, the ordering is optimized for lu(S(:,p)). It will
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% be a poor ordering for chol(S(:,p)'*S(:,p)). This is the most
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% important knob for ccolamd.
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% knobs(2): if S is m-by-n, rows with more than max(16,knobs(2)*sqrt(n))
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% entries are ignored.
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% knobs(3): columns with more than max(16,knobs(3)*sqrt(min(m,n))) entries
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% are ignored and ordered last in the output permutation (subject to the
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% cmember constraints).
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% knobs(4): if nonzero, aggressive absorption is performed.
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% knobs(5): if nonzero, statistics and knobs are printed.
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% cmember is an optional vector of length n. It defines the constraints on
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% the column ordering. If cmember(j)=s, then column j is in constraint set
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% s (s must be in the range 1 to n). In the output permutation p, all
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% columns in set 1 appear first, followed by all columns in set 2, and so
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% on. cmember=ones(1,n) if not present or empty. ccolamd(S,[],1:n) returns
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% p = ccolamd(S) is about the same as p = colamd(S). knobs and its default
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% values differ. colamd always does aggressive absorption, and it finds an
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% ordering suitable for both lu(S(:,p)) and chol(S(:,p)'*S(:,p)); it cannot
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% optimize its ordering for lu(S(:,p)) to the extent that ccolamd(S,1) can.
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% See also AMD, CSYMAMD, COLAMD, SYMAMD, SYMRCM.
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% Copyright 1998-2007, Timothy A. Davis, Stefan Larimore, and Siva Rajamanickam
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% Developed in collaboration with J. Gilbert and E. Ng.
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% Supported by the National Science Foundation (DMS-9504974, DMS-9803599,
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% CCR-0203270), and a grant from Sandia National Lab.
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error ('ccolamd: mexFunction not found') ;