From: Roy Stogner <roystgnr@ic...>  20100216 21:04:45

On Tue, 16 Feb 2010, Rahul Sampath wrote: > HEX8: 7 6 > oo > /: / > / : /  > 4 / : 5 /  > oo  >  o.......o 2 >  .3  / >  .  / > . / > oo > 0 1 > > TET4: > 3 > o > /\ > /  \ > /  \ > 0 o......o 2 > \  / > \  / > \/ > o > 1 > > However, you have not shown the coordinate axes. I need to know the following: > 1) The relationship between the local coordinate system and the local > node numbering scheme. For example, In Hex8 whether the edge 01 is > parallel to the local xi or eta axes. > > 2) The relationship between the physical global coordinate system and > the local coordinate system. > > I believe you must already be using some convention for both to be > able to compute the Jacobian of the transformation. It would be very > helpful if you could tell me where I can find this information. To the best of my recollection: For triangles and tets, the nodes are at (0,0,0), (1,0,0), (0,1,0), (0,0,1) in master coordinates For tensor product elements, the geometry is [1,1]^d and the edges are 01:xi, 03:eta, 04:zeta For pyramids, the peak is at (0,0,1) and the base is the same as a quad. Prisms are the tensor product of a triangle and an edge, with the triangle at zeta=1 given the lower local node numbers. I'm afraid that the only place where you can find this information solidly may be implicitly in the fe_lagrange*.C code, though; I'm not sure we've got it cleanly documented. If you'd like to add such documentation, a patch (in ASCII so we can put it in the headers) would be appreciated.  Roy 