How dolfin iterates through elements during the assembly process

Question

If I have a linear form defined only in a subdomain

F = inner(grad(u), grad(u))*dx(1)

When this form is assembled, does dolfin iterate through all the elements, then checks whether that element belongs to the subdomain that defines the measure dx(1) or not and assemble the form? Or it iterates only through the elements in subdomain?

Answer 1

Have a look at dolfin/fem/Assembler.cpp around line 156. Dolfin will iterate over all cells in the domain, and then skip the ones which are not in subdomain 1.

Comments

Thanks. Really appreciate your answer.