“…Although we work with continuous coordinate system which uses real numbers, our work is essential in discrete mathematics, especially, in digital geometry to work, e.g., with digital images on the triangular grid. We should also note that hexagonal, triangular, honeycomb and other related grid structures are used in various other fields, e.g., in networks [ 12 , 13 , 17 , 18 , 19 ], in fractional calculus [ 20 , 21 ], in 3D printing [ 22 ], in chemical and physical modelling [ 23 ] and simulations [ 24 , 25 ], and in city planning [ 26 ], where continuous transformations play also crucial roles, thus our result may be applied. Additionally to the above mentioned fields, triangular grid is applied in skeletonization and thinning algorithms [ 27 , 28 ], in discrete tomography [ 29 ] and in cartography.…”