I am trying to understand the 13-Node Pyramid Element as shown in Figure 11.13 and the accomaping shape function eqn 11–195 from the documentation. The problem I have are in the last two lines of the equation for u, as there the parenthesis given do not match. The last closing parenthesis has no opening counter part. I would like to know where that should be placed.

Further more, I'd like to understand what value the coordinate Z, for example, has in the reference pyramid element. Is it the same as the hex element (e.g. something like {1,1,0}) or is it the mid side of nodes J and M. I am asking because if you insert these values into the expression given either should return the value at UZ, but I am unable to get that.

I am sure am missing something simple, what is it? Thx.