### state variables

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Hi, I would like to save a variable "Igama" which is a scaler function of solution variable u1. I want to save its previous values in time to perform some operations. I defined "updatedamage" function but this does not work. Igama_n.assign(Igama) also does not work and gives an error message as underlined in the last row. How can I assign Igama to Igama_n correctly? Thank you !

mesh = UnitCubeMesh(1, 1, 1)

V = VectorFunctionSpace(mesh, "Lagrange", 1)

VF = FunctionSpace(mesh, "Lagrange", 1)

d = len(u1)

#d = u1.geometric_dimension()

I = Identity(d) # Identity tensor

F = I + grad(u1) # Deformation gradient

C = F.T*F # Right Cauchy-Green tensor

Cinv=inv(C)

Finv=inv(F)

J = det(F)

I1 = tr(C)

I2 = 0.5*(tr(C)**2-tr(dot(C,C)))

I3 = J**2.0

Jinv=J**(-1.0)

I1bar=I1/(I3**(1.0/3.0))

I2bar=I2/(I3**(2.0/3.0))

# Compute Igama

Igama = (2.0*(I1bar**2)-6.0*I2bar)

tolV=project(Constant("1E-14"),VF)

Igama=conditional(le(Igama,tolV), tolV, Igama) # required to avoid minus values in sqrt()

Igama = sqrt(Igama)/6.0

# Values of Igama at previous time

Igama_n=Function(VF)

# Update variables for t=t(n)

def updatedamage(Igama):

Igama_n = Igama

# Set up PDE

problem = NonlinearVariationalProblem(Fsol, u1, bcs=bc, J=dF)

solver = NonlinearVariationalSolver(problem)

#form_compiler_parameters={"quadrature_degree":1,"optimize":True,"eliminate_zeros":False}

#solver.parameters["linear_solver"] = "cg"

#solver.parameters["preconditioner"] = "ilu"

#prm = solver.parameters["krylov_solver"]

prm = solver.parameters["newton_solver"]

prm["absolute_tolerance"] = 1E-7

prm["relative_tolerance"] = 1E-7

prm["maximum_iterations"] = 100

#prm["newton_solver"]["relaxation_parameter"] = 0.1

# Solve

while t < T-dt:

t += dt

h.t=t

imposed.t=t

solver.solve()

updatedamage(Igama) # This definition does not update Igama_n

Igama_n.assign(Igama) # I get this error: Expects only linear combinations of Functions in the same FunctionSpaces.

mesh = UnitCubeMesh(1, 1, 1)

V = VectorFunctionSpace(mesh, "Lagrange", 1)

VF = FunctionSpace(mesh, "Lagrange", 1)

d = len(u1)

#d = u1.geometric_dimension()

I = Identity(d) # Identity tensor

F = I + grad(u1) # Deformation gradient

C = F.T*F # Right Cauchy-Green tensor

Cinv=inv(C)

Finv=inv(F)

J = det(F)

I1 = tr(C)

I2 = 0.5*(tr(C)**2-tr(dot(C,C)))

I3 = J**2.0

Jinv=J**(-1.0)

I1bar=I1/(I3**(1.0/3.0))

I2bar=I2/(I3**(2.0/3.0))

# Compute Igama

Igama = (2.0*(I1bar**2)-6.0*I2bar)

tolV=project(Constant("1E-14"),VF)

Igama=conditional(le(Igama,tolV), tolV, Igama) # required to avoid minus values in sqrt()

Igama = sqrt(Igama)/6.0

# Values of Igama at previous time

Igama_n=Function(VF)

# Update variables for t=t(n)

def updatedamage(Igama):

Igama_n = Igama

# Set up PDE

problem = NonlinearVariationalProblem(Fsol, u1, bcs=bc, J=dF)

solver = NonlinearVariationalSolver(problem)

#form_compiler_parameters={"quadrature_degree":1,"optimize":True,"eliminate_zeros":False}

#solver.parameters["linear_solver"] = "cg"

#solver.parameters["preconditioner"] = "ilu"

#prm = solver.parameters["krylov_solver"]

prm = solver.parameters["newton_solver"]

prm["absolute_tolerance"] = 1E-7

prm["relative_tolerance"] = 1E-7

prm["maximum_iterations"] = 100

#prm["newton_solver"]["relaxation_parameter"] = 0.1

# Solve

while t < T-dt:

t += dt

h.t=t

imposed.t=t

solver.solve()

updatedamage(Igama) # This definition does not update Igama_n

Igama_n.assign(Igama) # I get this error: Expects only linear combinations of Functions in the same FunctionSpaces.

Community: FEniCS Project

### 1 Answer

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Thank you , I tried the following:

def updatedamage(Igama, void, g, P):

Igama_np = project(Igama,VF)

Igama_n.vector()[:] = Igama_np.vector()

both worked well.

Regards,

Birkan

def updatedamage(Igama, void, g, P):

Igama_np = project(Igama,VF)

Igama_n.vector()[:] = Igama_np.vector()

both worked well.

Regards,

Birkan

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workingexample and use the proper syntax highlighting functions.At least the quantities u1, t, dt, T, h and imposed are not defined in your code (I stopped looking then). The import of fenics is not declared either.

As for your problem, try