% -*- texinfo -*-
% @deftypefn {Function File} {[@var{varargout}]} = MSH2Mtopprop(@var{mesh}, [@var{string1}, @var{string2},...])
%
% Computes some topological properties of the mesh @var{mesh}.
%
% Input:
% @itemize @minus
% @item @var{mesh}: mesh structure with (at least) fields @code{p},
% @code{e} and @code{t} a detailed in the help for @code{MSH2Mstructmesh}.
% @item @var{string1}, @var{string2},...: properties to compute,
% available choices are:
%
% @itemize @bullet
% @item 'n' (neighbouring triangles): a matrix @code{M} of size 3 by
% the number of elements. Element @code{M(i,j)} will be the index of
% the mesh element sharing with elemnt number @code{j} its
% @code{i}-th edge if no such element exists (i.e. for boundary
% edges) a value of @code{NaN} is set.
% @item 'sides' (global edge matrix): a matrix @code{M} of size 2 by
% total number of edges. Element @code{M(i,j)} will be the index of
% the vertex at the @code{i}-th end of the @code{j}-th edge.
% @item 'ts' (triangle sides matrix): a matrix @code{M} of size 3 by
% number of elements. Element @code{M(i,j)} will be the index of the
% @code{i}-th side of the @code{j}-th mesh element.
% @item 'tws' (trg with sides matrix):a matrix @code{M} of size 2 by
% the total number of edges.
% @code{M(:,j)} will the set of indeces of the mesh
% elements to whose boundary the @code{j}-th mesh edge belongs.
% For an edge @code{j} belonging to one triangle onlly (an external
% boundary edge) @code{M(2,j) = NaN}.
% @item 'coinc' (coincident circumcenter matrix): a matrix @code{M}
% with 2 rows.
% Each column will contain the indices of two triangles sharing the
% same circumcenter.
% @item 'boundary' (boundary edge matrix): a matrix @code{M} of size 2
% times the total number of boundary edges.
% @code{M(1,:)} will be the set of mesh elements (possibly repeated)
% with at least one edge belonging to the external boundary.
% @code{0 < M(2,j) < 4} will be the (local) index of an edge of the
% @code{j}-th mesh element that lies on the external boundary.
% @end itemize
% @end itemize
%
% The output will contain the geometrical properties requested in the input in the same order specified in the function call
% @seealso{MSHM2geomprop}
% @end deftypefn