Hi all! I know how to calculate the volume of the first order tetrahedron. But in the case of second order tetrahedra creating by gmsh for my complicated geometry (see one of these tetrahedra http://saveimg.ru/show-image.php?id=0971dc74b46b676f549960aebeae3e4b) I encountered a problem of finding the right volume of the tetrahedron. Can anybody help me? Thanks Mikhail Artemiev