This needs to be TrialFunctions(V) and TestFunctions(V) (notice the plural) An equivalent way of doing this is ugHp = TrialFunction(V) u, g, H, p = split(ugHp) Andrew On 24 June 2018 at 16:23, Amireh Mousavi <amireh.mousavi@math.iut.ac.ir> wrote:
Hi, for 4×4 system of PDEs, I considered trial and test functions mixed of 4 function spaces as the following: V1 = FunctionSpace(mesh, "CG", deg) V2 = VectorFunctionSpace(mesh, "CG", deg) V3 = TensorFunctionSpace(mesh, "CG", deg) P = FunctionSpace(mesh, "CG", deg) V = V1 * V2 * V3 * P u, g, H, p = TrialFunction(V) phi1, phi2, phi3, q = TestFunction(V)
but I got the following error
*Traceback (most recent call last): File "test1.py", line 58, in <module> u, g, H, p = TrialFunction(V) ValueError: too many values to unpack (expected 4)*
Many thanks if someone could give me some direction about that. Best, Amireh