First input is T, a Triplet list of indices -whom each row actually contains the three indices of a triangle vertices-. size(T) = [nb_triangles, 3]. Second input is e = [e1, e2], a row vector, couple of indices. Output S is the triplet list of indices which Share the edge e. For instance, if

e = [2, 4]

and T a tetrahedron

T = [1, 2, 3;...
     1, 3, 4;...
     1, 2, 4;...
     2, 3, 4]

then the output of the function is

S = [1, 2, 4;...
     2, 3, 4]

since both triangles [1, 2, 4] and [2, 3, 4] contain the edge [2, 4].

Conditions :

• If the edge is not part of any triangle in the list, the function must of course return the empty set, [].
• Edges are symmetric : [e1, e2] is the same edge as [e2, e1]
• Order of rows / edges in the output doesn't matter.
• Triangle indices are assumed always to be sorted in ascending order, T = [t1, t2, t3] with t1 < t2 < t3.
• Every indices are positive, distinct integers.