Locating a Point of Minimum Variance on Triangular Graphs

In this note the convexity of the variance measure for triangular graphs is established, and an expression for the point that minimizes the variance on an edge is given. A transformation of triangular graphs into trees provides an efficient means to implement these properties via a postorder search of a tree. The result is a linear time algorithm that determines a point of minimum variance for any triangular graph whose edge lengths satisfy the triangle inequality.