Random Distances Associated with Rhombuses
  Parallelograms are one of the basic building blocks in two-dimensional tiling. They have important applications in a wide variety of science and engineering fields, such as wireless communication networks, urban transportation, operations research, etc. Different from rectangles and squares, the coordinates of a random point in parallelograms are no longer independent. As a case study of parallelograms, the explicit probability density functions of the random Euclidean distances associated with rhombuses are given in this report, when both endpoints are randomly distributed in 1) the same rhombus, 2) two parallel rhombuses sharing a side, and 3) two rhombuses having a common diagonal, respectively. The accuracy of the distance distribution functions is verified by simulation, and the correctness is validated by a recursion and a probabilistic sum. The first two statistical moments of the random distances, and the polynomial fit of the density functions are also given in this report for practical uses. 
Yanyan Zhuang and Jianping Pan
math.GM cs.NI