1function [p, cparent, cmember] = nesdis (A, mode, opts)			    %#ok
2%NESDIS nested dissection ordering via CHOLMOD's nested dissection.
3%
4%   Example:
5%   p = nesdis(A)         returns p such chol(A(p,p)) is typically sparser than
6%                         chol(A).  Uses tril(A) and assumes A is symmetric.
7%   p = nesdis(A,'sym')   the same as p=nesdis(A).
8%   p = nesdis(A,'col')   returns p so that chol(A(:,p)'*A(:,p)) is typically
9%                         sparser than chol(A'*A).
10%   p = nesdis(A,'row')   returns p so that chol(A(p,:)*A(p,:)') is typically
11%                         sparser than chol(A'*A).
12%
13%   A must be square for p=nesdis(A) or nesdis(A,'sym').
14%
15%   With three output arguments, [p cp cmember] = nesdis(...), the separator
16%   tree and node-to-component mapping is returned.  cmember(i)=c means that
17%   node i is in component c, where c is in the range of 1 to the number of
18%   components.  length(cp) is the number of components found.  cp is the
19%   separator tree; cp(c) is the parent of component c, or 0 if c is a root.
20%   There can be anywhere from 1 to n components, where n is dimension of A,
21%   A*A', or A'*A.  cmember is a vector of length n.
22%
23%   An optional 3rd input argument, nesdis (A,mode,opts), modifies the default
24%   parameters.  opts(1) specifies the smallest subgraph that should not be
25%   partitioned (default is 200).  opts(2) is 0 by default; if nonzero,
26%   connected components (formed after the node separator is removed) are
27%   partitioned independently.  The default value tends to lead to a more
28%   balanced separator tree, cp.  opts(3) defines when a separator is kept; it
29%   is kept if the separator size is < opts(3) times the number of nodes in the
30%   graph being cut (valid range is 0 to 1, default is 1).
31%
32%   opts(4) specifies graph is to be ordered after it is dissected.  For the
33%   'sym' case: 0: natural ordering, 1: CAMD, 2: CSYMAMD.  For other cases:
34%   0: natural ordering, nonzero: CCOLAMD.  The default is 1, to use CAMD for
35%   the symmetric case and CCOLAMD for the other cases.
36%
37%   If opts is shorter than length 4, defaults are used for entries
38%   that are not present.
39%
40%   NESDIS uses METIS' node separator algorithm to recursively partition the
41%   graph.  This gives a set of constraints (cmember) that is then passed to
42%   CCOLAMD, CSYMAMD, or CAMD, constrained minimum degree ordering algorithms.
43%   NESDIS typically takes slightly more time than METIS (METIS_NodeND), but
44%   tends to produce better orderings.
45%
46%   Requires METIS, authored by George Karypis, Univ. of Minnesota.  This
47%   MATLAB interface, via CHOLMOD, is by Tim Davis.
48%
49%   See also METIS, BISECT, AMD
50
51%   Copyright 2006-2007, Timothy A. Davis, http://www.suitesparse.com
52
53error ('nesdis mexFunction not found') ;
54