def test_model_solver_minimize(self):
# Create model
model = pybamm.BaseModel()
whole_cell = ["negative electrode", "separator", "positive electrode"]
var1 = pybamm.Variable("var1", domain=whole_cell)
var2 = pybamm.Variable("var2", domain=whole_cell)
model.algebraic = {var1: var1 - 3, var2: 2 * var1 - var2}
model.initial_conditions = {var1: pybamm.Scalar(1), var2: pybamm.Scalar(4)}
model.variables = {"var1": var1, "var2": var2}
disc = get_discretisation_for_testing()
disc.process_model(model)
sol = np.concatenate((np.ones(100) * 3, np.ones(100) * 6))[:, np.newaxis]
# Solve
solver = pybamm.AlgebraicSolver("minimize", tol=1e-8)
solution = solver.solve(model)
np.testing.assert_array_almost_equal(
model.variables["var1"].evaluate(t=None, y=solution.y), sol[:100]
)
np.testing.assert_array_almost_equal(
model.variables["var2"].evaluate(t=None, y=solution.y), sol[100:]
)
# Test without jacobian and with a different method
model.use_jacobian = False
solver = pybamm.AlgebraicSolver("minimize__BFGS")
solution_no_jac = solver.solve(model)
np.testing.assert_array_almost_equal(
model.variables["var1"].evaluate(t=None, y=solution_no_jac.y), sol[:100]
)
np.testing.assert_array_almost_equal(
model.variables["var2"].evaluate(t=None, y=solution_no_jac.y), sol[100:]
)
def test_root_find_fail(self):
class Model:
y0 = np.array([2])
rhs = {}
timescale_eval = 1
length_scales = {}
jac_algebraic_eval = None
convert_to_format = "casadi"
def algebraic_eval(self, t, y, inputs):
# algebraic equation has no real root
return y ** 2 + 1
model = Model()
solver = pybamm.AlgebraicSolver(method="hybr")
with self.assertRaisesRegex(
pybamm.SolverError,
"Could not find acceptable solution: The iteration is not making",
):
solver._integrate(model, np.array([0]))
solver = pybamm.AlgebraicSolver()
with self.assertRaisesRegex(
pybamm.SolverError, "Could not find acceptable solution: solver terminated"
):
solver._integrate(model, np.array([0]))
def test_model_solver_with_time(self):
# Create model
model = pybamm.BaseModel()
var1 = pybamm.Variable("var1")
var2 = pybamm.Variable("var2")
model.algebraic = {var1: var1 - 3 * pybamm.t, var2: 2 * var1 - var2}
model.initial_conditions = {var1: pybamm.Scalar(1), var2: pybamm.Scalar(4)}
model.variables = {"var1": var1, "var2": var2}
disc = pybamm.Discretisation()
disc.process_model(model)
# Solve
t_eval = np.linspace(0, 1)
solver = pybamm.AlgebraicSolver()
solution = solver.solve(model, t_eval)
sol = np.vstack((3 * t_eval, 6 * t_eval))
np.testing.assert_array_equal(solution.y, sol)
np.testing.assert_array_equal(
model.variables["var1"].evaluate(t=t_eval, y=solution.y).flatten(),
sol[0, :],
)
np.testing.assert_array_equal(
model.variables["var2"].evaluate(t=t_eval, y=solution.y).flatten(),
sol[1, :],
)
def test_solver_citations(self):
# Test that solving each solver adds the right citations
citations = pybamm.citations
citations._reset()
self.assertNotIn("virtanen2020scipy", citations._papers_to_cite)
pybamm.ScipySolver()
self.assertIn("virtanen2020scipy", citations._papers_to_cite)
citations._reset()
self.assertNotIn("virtanen2020scipy", citations._papers_to_cite)
pybamm.AlgebraicSolver()
self.assertIn("virtanen2020scipy", citations._papers_to_cite)
if pybamm.have_scikits_odes():
citations._reset()
self.assertNotIn("scikits-odes", citations._papers_to_cite)
pybamm.ScikitsOdeSolver()
self.assertIn("scikits-odes", citations._papers_to_cite)
citations._reset()
self.assertNotIn("scikits-odes", citations._papers_to_cite)
pybamm.ScikitsDaeSolver()
self.assertIn("scikits-odes", citations._papers_to_cite)
if pybamm.have_idaklu():
citations._reset()
self.assertNotIn("hindmarsh2005sundials",
citations._papers_to_cite)
pybamm.IDAKLUSolver()
self.assertIn("hindmarsh2005sundials", citations._papers_to_cite)
def test_root_find_fail(self):
def algebraic(y):
# algebraic equation has no real root
return y**2 + 1
solver = pybamm.AlgebraicSolver(method="hybr")
y0 = np.array([2])
with self.assertRaisesRegex(
pybamm.SolverError,
"Could not find acceptable solution: The iteration is not making",
):
solver.root(algebraic, y0)
solver = pybamm.AlgebraicSolver()
with self.assertRaisesRegex(
pybamm.SolverError,
"Could not find acceptable solution: solver terminated"):
solver.root(algebraic, y0)
def test_simple_root_find(self):
# Simple system: a single algebraic equation
def algebraic(y):
return y + 2
solver = pybamm.AlgebraicSolver()
y0 = np.array([2])
solution = solver.root(algebraic, y0)
np.testing.assert_array_equal(solution.y, -2)
def test_algebraic_solver_init(self):
solver = pybamm.AlgebraicSolver(method="hybr", tol=1e-4)
self.assertEqual(solver.method, "hybr")
self.assertEqual(solver.tol, 1e-4)
solver.method = "krylov"
self.assertEqual(solver.method, "krylov")
solver.tol = 1e-5
self.assertEqual(solver.tol, 1e-5)
def root_method(self, method):
if method == "casadi":
method = pybamm.CasadiAlgebraicSolver(self.root_tol)
elif isinstance(method, str):
method = pybamm.AlgebraicSolver(method, self.root_tol)
elif not (method is None or (isinstance(method, pybamm.BaseSolver)
and method.algebraic_solver is True)):
raise pybamm.SolverError("Root method must be an algebraic solver")
self._root_method = method
def test_algebraic_solver_init(self):
solver = pybamm.AlgebraicSolver(
method="hybr", tol=1e-4, extra_options={"maxfev": 100}
)
self.assertEqual(solver.method, "hybr")
self.assertEqual(solver.extra_options, {"maxfev": 100})
self.assertEqual(solver.tol, 1e-4)
solver.method = "krylov"
self.assertEqual(solver.method, "krylov")
solver.tol = 1e-5
self.assertEqual(solver.tol, 1e-5)
def test_simple_root_find(self):
# Simple system: a single algebraic equation
class Model:
y0 = np.array([2])
rhs = {}
timescale_eval = 1
jac_algebraic_eval = None
convert_to_format = "python"
def algebraic_eval(self, t, y, inputs):
return y + 2
# Try passing extra options to solver
solver = pybamm.AlgebraicSolver(extra_options={"maxiter": 100})
model = Model()
solution = solver._integrate(model, np.array([0]))
np.testing.assert_array_equal(solution.y, -2)
# Relax options and see worse results
solver = pybamm.AlgebraicSolver(extra_options={"ftol": 1})
solution = solver._integrate(model, np.array([0]))
self.assertNotEqual(solution.y, -2)
def test_simple_root_find(self):
# Simple system: a single algebraic equation
class Model:
y0 = np.array([2])
jacobian_eval = None
convert_to_format = "python"
def algebraic_eval(self, t, y, inputs):
return y + 2
solver = pybamm.AlgebraicSolver()
model = Model()
solution = solver._integrate(model, np.array([0]))
np.testing.assert_array_equal(solution.y, -2)
def test_wrong_solver(self):
# Create model
model = pybamm.BaseModel()
var = pybamm.Variable("var")
model.rhs = {var: var}
model.algebraic = {var: var - 1}
# test errors
solver = pybamm.AlgebraicSolver()
with self.assertRaisesRegex(
pybamm.SolverError,
"Cannot use algebraic solver to solve model with time derivatives",
):
solver.solve(model)
def test_solve_with_input(self):
# Simple system: a single algebraic equation
var = pybamm.Variable("var")
model = pybamm.BaseModel()
model.algebraic = {var: var + pybamm.InputParameter("value")}
model.initial_conditions = {var: 2}
# create discretisation
disc = pybamm.Discretisation()
disc.process_model(model)
# Solve
solver = pybamm.AlgebraicSolver()
solution = solver.solve(model, np.linspace(0, 1, 10), inputs={"value": 7})
np.testing.assert_array_equal(solution.y, -7)
def test_root_method_init(self):
solver = pybamm.BaseSolver(root_method="casadi")
self.assertIsInstance(solver.root_method, pybamm.CasadiAlgebraicSolver)
solver = pybamm.BaseSolver(root_method="lm")
self.assertIsInstance(solver.root_method, pybamm.AlgebraicSolver)
self.assertEqual(solver.root_method.method, "lm")
root_solver = pybamm.AlgebraicSolver()
solver = pybamm.BaseSolver(root_method=root_solver)
self.assertEqual(solver.root_method, root_solver)
with self.assertRaisesRegex(pybamm.SolverError,
"Root method must be an algebraic solver"):
pybamm.BaseSolver(root_method=pybamm.ScipySolver())
def test_pure_neumann_poisson(self):
# grad^2 u = 1, du/dz = 1 at z = 1, du/dn = 0 elsewhere, u has zero average
u = pybamm.Variable("u", domain="current collector")
c = pybamm.Variable("c") # lagrange multiplier
y = pybamm.SpatialVariable("y", ["current collector"])
z = pybamm.SpatialVariable("z", ["current collector"])
model = pybamm.BaseModel()
# 0*c hack otherwise gives KeyError
model.algebraic = {
u:
pybamm.laplacian(u) - pybamm.source(1, u) +
c * pybamm.DefiniteIntegralVector(u, vector_type="column"),
c:
pybamm.Integral(u, [y, z]) + 0 * c,
}
model.initial_conditions = {u: pybamm.Scalar(0), c: pybamm.Scalar(0)}
# set boundary conditions ("negative tab" = bottom of unit square,
# "positive tab" = top of unit square, elsewhere normal derivative is zero)
model.boundary_conditions = {
u: {
"negative tab": (0, "Neumann"),
"positive tab": (1, "Neumann")
}
}
model.variables = {"c": c, "u": u}
# create discretisation
mesh = get_unit_2p1D_mesh_for_testing(ypts=32,
zpts=32,
include_particles=False)
spatial_methods = {
"macroscale": pybamm.FiniteVolume(),
"current collector": pybamm.ScikitFiniteElement(),
}
disc = pybamm.Discretisation(mesh, spatial_methods)
disc.process_model(model)
# solve model
solver = pybamm.AlgebraicSolver()
solution = solver.solve(model)
z = mesh["current collector"].coordinates[1, :][:, np.newaxis]
u_exact = z**2 / 2 - 1 / 6
np.testing.assert_array_almost_equal(solution.y[:-1],
u_exact,
decimal=1)
def test_model_solver_minimize_with_bounds(self):
# Note: we need a better test case to test this functionality properly
# Create model
model = pybamm.BaseModel()
var1 = pybamm.Variable("var1", bounds=(0, 10))
model.algebraic = {var1: pybamm.sin(var1) + 1}
model.initial_conditions = {var1: pybamm.Scalar(3)}
model.variables = {"var1": var1}
# Solve
solver = pybamm.AlgebraicSolver("minimize", tol=1e-16)
solution = solver.solve(model)
np.testing.assert_array_almost_equal(
model.variables["var1"].evaluate(t=None, y=solution.y),
3 * np.pi / 2,
decimal=4,
)
def test_with_jacobian(self):
A = np.array([[4, 3], [1, -1]])
b = np.array([0, 7])
def algebraic(y):
return A @ y - b
def jac(y):
return A
y0 = np.zeros(2)
sol = np.array([3, -4])[:, np.newaxis]
solver = pybamm.AlgebraicSolver()
solution_no_jac = solver.root(algebraic, y0)
solution_with_jac = solver.root(algebraic, y0, jacobian=jac)
np.testing.assert_array_almost_equal(solution_no_jac.y, sol)
np.testing.assert_array_almost_equal(solution_with_jac.y, sol)
def test_with_jacobian(self):
A = np.array([[4, 3], [1, -1]])
b = np.array([0, 7])
class Model:
y0 = np.zeros(2)
convert_to_format = "python"
def algebraic_eval(self, t, y, inputs):
return A @ y - b
def jacobian_eval(self, t, y, inputs):
return A
model = Model()
sol = np.array([3, -4])[:, np.newaxis]
solver = pybamm.AlgebraicSolver()
solution = solver._integrate(model, np.array([0]))
np.testing.assert_array_almost_equal(solution.y, sol)
def test_dirichlet_bcs(self):
# manufactured solution u = a*z^2 + b*z + c
model = pybamm.BaseModel()
a = 3
b = 4
c = 5
u = pybamm.Variable("variable", domain="current collector")
model.algebraic = {u: -pybamm.laplacian(u) + pybamm.source(2 * a, u)}
# set boundary conditions ("negative tab" = bottom of unit square,
# "positive tab" = top of unit square, elsewhere normal derivative is zero)
model.boundary_conditions = {
u: {
"negative tab": (pybamm.Scalar(c), "Dirichlet"),
"positive tab": (pybamm.Scalar(a + b + c), "Dirichlet"),
}
}
# bad initial guess (on purpose)
model.initial_conditions = {u: pybamm.Scalar(1)}
model.variables = {"u": u}
# create discretisation
mesh = get_unit_2p1D_mesh_for_testing(ypts=8,
zpts=32,
include_particles=False)
spatial_methods = {
"macroscale": pybamm.FiniteVolume(),
"current collector": pybamm.ScikitFiniteElement(),
}
disc = pybamm.Discretisation(mesh, spatial_methods)
disc.process_model(model)
# solve model
solver = pybamm.AlgebraicSolver()
solution = solver.solve(model)
# indepedent of y, so just check values for one y
z = mesh["current collector"].edges["z"][:, np.newaxis]
u_exact = a * z**2 + b * z + c
np.testing.assert_array_almost_equal(solution.y[0:len(z)], u_exact)
def default_solver(self):
return pybamm.AlgebraicSolver()
def default_solver(self):
# Use AlgebraicSolver as CasadiAlgebraicSolver gives unnecessary warnings
return pybamm.AlgebraicSolver()
}
mesh = pybamm.Mesh(geometry, model.default_submesh_types, var_pts)
cc_mesh = pybamm.Mesh(cc_geometry, cc_model.default_submesh_types, var_pts)
disc = pybamm.Discretisation(mesh, models[0].default_spatial_methods)
cc_disc = pybamm.Discretisation(cc_mesh, cc_models[0].default_spatial_methods)
disc.process_model(model, check_model=False)
cc_disc.process_model(cc_model, check_model=False)
# solve
tau = param.evaluate(pybamm.standard_parameters_lithium_ion.tau_discharge)
time = comsol_t / tau
solver = pybamm.CasadiSolver(
atol=1e-6, rtol=1e-6, root_tol=1e-3, root_method="hybr", mode="fast"
)
solution = solver.solve(model, time)
cc_solver = pybamm.AlgebraicSolver(tol=1e-6)
cc_solution = cc_solver.solve(cc_model)
sol_times[i] = solution.solve_time + cc_solution.solve_time
# create comsol vars interpolated onto pybamm mesh to compare errors
comsol_model = shared.make_comsol_model(
comsol_variables, cc_mesh, param, thermal=True
)
# compute "error" using times up to voltage cut off
t = solution.t
# Note: casadi doesnt support events so we find this time after the solve
if isinstance(solver, pybamm.CasadiSolver):
V_cutoff = param.evaluate(
pybamm.standard_parameters_lithium_ion.voltage_low_cut_dimensional
)
