tricnt

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function [t,d,w] = tricnt(G,d,matlabbgl)

%TRICNT Count number of triangles per vertex in a simple, undirected graph
%
%   T = TRICNT(G) takes a sparse adjacency matrix G and computes the number
%   of triangles per vertex. Note taht there is no error checking on G. It
%   is up to the user to ensure that G is symmetric, has only 0/1 entries
%   (but *not* binary), and has no entries on the diagonal.
%
%   T = TRICNT(G,D) takes a second argument which is the degree per vertex
%   and does not recalculate it.
%
%   T = TRICNT(G,D,true) uses the clustering_coefficients from MATLAB_BGL.
%   This assumes that this package is installed and in the path.
%
%   [T,D,W] = TRICNT(G) also returns the degree and number of wedges per
%   vertex.
%
%   NOTE: This is an interface to the MEX function provided by
%   tricnt_mex.c, unless the clustering_coefficients function from
%   MATLAB_BGL is used.
%
%   See also CCPERDEG.
%
% Tamara G. Kolda, Ali Pinar, and others, FEASTPACK v1.1, Sandia National
% Laboratories, SAND2013-4136W, http://www.sandia.gov/~tgkolda/feastpack/,
% January 2014

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Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

if ~exist('matlabbgl','var')
    matlabbgl = false;
end

if ~exist('d','var') || isempty(d)
    d = full(sum(G,2));
end

w = d.*(d-1)/2;

if (matlabbgl)

    if ~exist('clustering_coefficients.m','file')
        error('Must install MATLAB_BGL toolbox');
    end
    options.undirected = 1;
    options.unweighted = 1;
    cc = clustering_coefficients(G,options);
    t = round(w.*cc);

else

    t = tricnt_mex(G);

end

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