Approximation of conservative fields and the element `edge shape matrix´

The accuracy of finite element approximation on tetrahedral elements is studied using the previously derived maximum eigenvalue condition. This condition is linked with the minimum singular value of the element `edge shape matrix´ that characterizes the flatness of an element. A geometric interpretation of these results is discussed. From the theoretical viewpoint, a better insight into the mechanism of approximation errors is gained. From the practical perspective, a precise characterization of shape of tetrahedral elements becomes possible