Hi,

I have the following issue. Let V be a discrete space and C: V → V a matrix mapping the coefficients of a function u in V to the coefficients Cu of a function in V. Now I want to solve the problem: Seek u in V with int Cu * Cv dx = int f Cv dx for all v in V. An example is given below. How can I do this?

from dolfin import *

mesh = UnitSquareMesh(4,4)

V = FunctionSpace(mesh,‘P’,1)

u = TrialFunction(V)

v = TestFunction(V)

#Create some PETScMatrix C: V → V (does not make so much sense here,

#but exemplifies what I want to do)

a = inner(u,v)*dx

dummy = Constant(0.0)vdx

C = PETScMatrix()

assemble_system(a,dummy,A_tensor=C)

#b = inner(C u,C v)*dx # this is how my mapping should look like

b = inner(u,v)*dx # just a dummy to have an executable code

L = Constant(1.0)vdx

uh = Function(V)

solve(b == L,uh)