I want use a function f(x) in the weak form, where x is a vector(function that defined on function space) which is equal to X (position vector) plus u ( the solution of the problem, trail function), and f() is a function that defined on function space by image( there is a scalar value for every single point, which means it does not have explicit expression).
I failed in using this function. Do you have some advices about achieving this function?
Thank you for your help!
