the aspect ratio of a perfect, tetrahedral element is used as the basis for calculating aspect ratios of other elements. The aspect ratio of an element is defined as the ratio between the longest edge and the shortest normal dropped from a vertex to the opposite face normalized with respect to a perfect tetrahedral. By definition, the aspect ratio of a perfect tetrahedral element is 1.0. The aspect-ratio chect is automatically used by the program to check the quality of the mesh and assumes straight edges connecting the four corner nodes.