Returns \(I(\)pt2 is in \(N_{CS}(pt1,t=1))\) for points pt1 and pt2,
that is, returns 1 if pt2 is in \(N_{CS}(pt1,t=1)\),
returns 0 otherwise, where \(N_{CS}(x,t=1)\) is the CS proximity region for point \(x\) with expansion parameter \(t=1\).
CS proximity region is defined with respect to the standard equilateral triangle
\(T_e=T(A,B,C)=T((0,0),(1,0),(1/2,\sqrt{3}/2))\) and edge regions are based on the center of mass \(CM=(1/2,\sqrt{3}/6)\).
Here pt1 must lie in the first one-sixth of \(T_e\), which is the triangle with vertices \(T(A,D_3,CM)=T((0,0),(1/2,0),CM)\).
If pt1 and pt2 are distinct and pt1 is outside of \(T(A,D_3,CM)\) or pt2 is outside \(T_e\), it returns 0,
but if they are identical, then it returns 1 regardless of their locations (i.e., it allows loops).
IndCS.Te.onesixth(pt1, pt2)A 2D point whose CS proximity region is constructed.
A 2D point. The function determines whether pt2 is inside the CS proximity region of
pt1 or not.
\(I(\)pt2 is in \(N_{CS}(pt1,t=1))\) for pt1 in the first one-sixth of \(T_e\),
\(T(A,D_3,CM)\), that is, returns 1 if pt2 is in \(N_{CS}(pt1,t=1)\), returns 0 otherwise