Returns the number of arcs of Arc Slice Proximity Catch Digraphs (AS-PCDs)
whose vertices are the 2D data set, dat. The data points could be inside or outside a general
triangle tri\(=T(A,B,C)=\)(rv=1,rv=2,rv=3), with vertices of tri stacked row-wise.
AS proximity regions are defined with respect to the triangle tri and vertex regions are
based on the center M="CC" for circumcenter of tri;
or \(M=(m_1,m_2)\) in Cartesian coordinates or \(M=(\alpha,\beta,\gamma)\) in barycentric coordinates in the
interior of the triangle tri; default is M="CC" i.e., circumcenter of tri.
For the number of arcs, loops are not allowed,
so arcs are only possible for points inside the triangle, tri.
See also (ceyhan:Phd-thesis,ceyhan:comp-geo-2010,ceyhan:mcap2012;textualpcds).