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function [x,stats] = cholmod2 (A, b, ordering) %#ok
%CHOLMOD2 supernodal sparse Cholesky backslash, x = A\b
%
% Example:
% x = cholmod2 (A,b)
%
% Computes the LL' factorization of A(p,p), where p is a fill-reducing
% ordering, then solves a sparse linear system Ax=b. A must be sparse,
% symmetric, and positive definite). Uses only the upper triangular part
% of A. A second output, [x,stats]=cholmod2(A,b), returns statistics:
%
% stats(1) estimate of the reciprocal of the condition number
% stats(2) ordering used:
% 0: natural, 1: given, 2:amd, 3:metis, 4:nesdis,
% 5:colamd, 6: natural but postordered.
% stats(3) nnz(L)
% stats(4) flop count in Cholesky factorization. Excludes solution
% of upper/lower triangular systems, which can be easily
% computed from stats(3) (roughly 4*nnz(L)*size(b,2)).
% stats(5) memory usage in MB.
%
% The 3rd argument select the ordering method to use. If not present or -1,
% the default ordering strategy is used (AMD, and then try METIS if AMD finds
% an ordering with high fill-in, and use the best method tried).
%
% Other options for the ordering parameter:
%
% 0 natural (no etree postordering)
% -1 use CHOLMOD's default ordering strategy (AMD, then try METIS)
% -2 AMD, and then try NESDIS (not METIS) if AMD has high fill-in
% -3 use AMD only
% -4 use METIS only
% -5 use NESDIS only
% -6 natural, but with etree postordering
% p user permutation (vector of size n, with a permutation of 1:n)
%
% See also CHOL, MLDIVIDE.
% Copyright 2006-2007, Timothy A. Davis, http://www.suitesparse.com
error ('cholmod2 mexFunction not found\n') ;
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