UFL Form names

Question

What are the "valid" Form names in UFL? If I take this example and compile it with ffc I get a Form_M in the header file. However if I change M to G it doesn't compile (while with a, L, F it works).

element = FiniteElement("Lagrange", triangle, 2)
v = Coefficient(element)
M = (v*v + dot(grad(v), grad(v)))*dx

Answer 1

The default valid form names seem to be a, L, M (and in certain conditions, F and J), but you can define more by adding a forms list to the bottom of your UFL file, for example, to use G instead of M:

element = FiniteElement("Lagrange", triangle, 2)
v = Coefficient(element)
G = (v*v + dot(grad(v), grad(v)))*dx
forms = [G]

which will result in Form_G in the header file.

See this section in the UFL documentation for more information. I believe the relevant section of the UFL source code which defines the default forms to be exported is here.

Comments

Nice digging :)