def test_model_solver_dae_inputs_events(self):
# Create model
for form in ["python", "casadi"]:
model = pybamm.BaseModel()
model.convert_to_format = form
whole_cell = ["negative electrode", "separator", "positive electrode"]
var1 = pybamm.Variable("var1", domain=whole_cell)
var2 = pybamm.Variable("var2", domain=whole_cell)
model.rhs = {var1: pybamm.InputParameter("rate 1") * var1}
model.algebraic = {var2: pybamm.InputParameter("rate 2") * var1 - var2}
model.initial_conditions = {var1: 1, var2: 2}
model.events = [
pybamm.Event("var1 = 1.5", pybamm.min(var1 - 1.5)),
pybamm.Event("var2 = 2.5", pybamm.min(var2 - 2.5)),
]
disc = get_discretisation_for_testing()
disc.process_model(model)
# Solve
if form == "python":
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8, root_method="lm")
else:
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
t_eval = np.linspace(0, 5, 100)
solution = solver.solve(model, t_eval, inputs={"rate 1": 0.1, "rate 2": 2})
np.testing.assert_array_less(solution.y[0], 1.5)
np.testing.assert_array_less(solution.y[-1], 2.5)
np.testing.assert_allclose(solution.y[0], np.exp(0.1 * solution.t))
np.testing.assert_allclose(solution.y[-1], 2 * np.exp(0.1 * solution.t))
def test_dae_integrate(self):
# Constant
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
def constant_growth_dae(t, y, ydot):
return [0.5 * np.ones_like(y[0]) - ydot[0], 2 * y[0] - y[1]]
y0 = np.array([0, 0])
t_eval = np.linspace(0, 1, 100)
solution = solver.integrate(constant_growth_dae, y0, t_eval)
np.testing.assert_array_equal(solution.t, t_eval)
np.testing.assert_allclose(0.5 * solution.t, solution.y[0])
np.testing.assert_allclose(1.0 * solution.t, solution.y[1])
# Exponential decay
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
def exponential_decay_dae(t, y, ydot):
return [-0.1 * y[0] - ydot[0], 2 * y[0] - y[1]]
y0 = np.array([1, 2])
t_eval = np.linspace(0, 1, 100)
solution = solver.integrate(exponential_decay_dae, y0, t_eval)
np.testing.assert_allclose(solution.y[0], np.exp(-0.1 * solution.t))
np.testing.assert_allclose(solution.y[1],
2 * np.exp(-0.1 * solution.t))
self.assertEqual(solution.termination, "final time")
def test_dae_integrate_with_event(self):
# Constant
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
def constant_growth_dae(t, y, ydot):
return [0.5 * np.ones_like(y[0]) - ydot[0], 2 * y[0] - y[1]]
def y0_eq_2(t, y):
return y[0] - 2
def y1_eq_5(t, y):
return y[1] - 5
y0 = np.array([0, 0])
t_eval = np.linspace(0, 7, 100)
solution = solver.integrate(constant_growth_dae,
y0,
t_eval,
events=[y0_eq_2, y1_eq_5])
self.assertLess(len(solution.t), len(t_eval))
np.testing.assert_allclose(0.5 * solution.t, solution.y[0])
np.testing.assert_allclose(1.0 * solution.t, solution.y[1])
np.testing.assert_array_less(solution.y[0], 2)
np.testing.assert_array_less(solution.y[1], 5)
np.testing.assert_allclose(solution.t_event, 4)
np.testing.assert_allclose(solution.y_event[0], 2)
np.testing.assert_allclose(solution.y_event[1], 4)
self.assertEqual(solution.termination, "event")
# Exponential decay
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
def exponential_decay_dae(t, y, ydot):
return np.array([-0.1 * y[0] - ydot[0], 2 * y[0] - y[1]])
def y0_eq_0pt9(t, y):
return y[0] - 0.9
def t_eq_0pt5(t, y):
return t - 0.5
y0 = np.array([1, 2])
t_eval = np.linspace(0, 1, 100)
solution = solver.integrate(exponential_decay_dae,
y0,
t_eval,
events=[y0_eq_0pt9, t_eq_0pt5])
self.assertLess(len(solution.t), len(t_eval))
np.testing.assert_allclose(solution.y[0], np.exp(-0.1 * solution.t))
np.testing.assert_allclose(solution.y[1],
2 * np.exp(-0.1 * solution.t))
np.testing.assert_array_less(0.9, solution.y[0])
np.testing.assert_array_less(solution.t, 0.5)
np.testing.assert_allclose(solution.t_event, 0.5)
np.testing.assert_allclose(solution.y_event[0], np.exp(-0.1 * 0.5))
np.testing.assert_allclose(solution.y_event[1], 2 * np.exp(-0.1 * 0.5))
self.assertEqual(solution.termination, "event")
def test_model_solver_dae_with_jacobian(self):
# Create simple test 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.rhs = {var1: 0.1 * var1}
model.algebraic = {var2: 2 * var1 - var2}
model.initial_conditions = {var1: 1.0, var2: 2.0}
model.initial_conditions_ydot = {var1: 0.1, var2: 0.2}
disc = get_discretisation_for_testing()
disc.process_model(model)
# Add user-supplied Jacobian to model
mesh = get_mesh_for_testing()
combined_submesh = mesh.combine_submeshes("negative electrode",
"separator",
"positive electrode")
N = combined_submesh[0].npts
def jacobian(t, y):
return np.block([
[0.1 * np.eye(N), np.zeros((N, N))],
[2.0 * np.eye(N), -1.0 * np.eye(N)],
])
# Solve
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
t_eval = np.linspace(0, 1, 100)
solution = solver.solve(model, t_eval)
np.testing.assert_array_equal(solution.t, t_eval)
np.testing.assert_allclose(solution.y[0], np.exp(0.1 * solution.t))
np.testing.assert_allclose(solution.y[-1],
2 * np.exp(0.1 * solution.t))
def test_model_step_dae_python(self):
model = pybamm.BaseModel()
model.convert_to_format = "python"
whole_cell = ["negative electrode", "separator", "positive electrode"]
var1 = pybamm.Variable("var1", domain=whole_cell)
var2 = pybamm.Variable("var2", domain=whole_cell)
model.rhs = {var1: 0.1 * var1}
model.algebraic = {var2: 2 * var1 - var2}
model.initial_conditions = {var1: 1, var2: 2}
model.use_jacobian = False
disc = get_discretisation_for_testing()
disc.process_model(model)
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8, root_method="lm")
# Step once
dt = 1
step_sol = solver.step(None, model, dt)
np.testing.assert_array_equal(step_sol.t, [0, dt])
np.testing.assert_allclose(step_sol.y[0], np.exp(0.1 * step_sol.t))
np.testing.assert_allclose(step_sol.y[-1], 2 * np.exp(0.1 * step_sol.t))
# Step again (return 5 points)
step_sol_2 = solver.step(step_sol, model, dt, npts=5)
np.testing.assert_array_equal(
step_sol_2.t, np.concatenate([np.array([0]), np.linspace(dt, 2 * dt, 5)])
)
np.testing.assert_allclose(step_sol_2.y[0], np.exp(0.1 * step_sol_2.t))
np.testing.assert_allclose(step_sol_2.y[-1], 2 * np.exp(0.1 * step_sol_2.t))
# Check steps give same solution as solve
t_eval = step_sol.t
solution = solver.solve(model, t_eval)
np.testing.assert_allclose(solution.y[0], step_sol.y[0, :])
np.testing.assert_allclose(solution.y[-1], step_sol.y[-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 default_solver(self):
"""
Create and return the default solver for this model
"""
# Default solver to DAE
return pybamm.ScikitsDaeSolver()
def test_model_solver_dae_events_python(self):
model = pybamm.BaseModel()
model.convert_to_format = "python"
whole_cell = ["negative electrode", "separator", "positive electrode"]
var1 = pybamm.Variable("var1", domain=whole_cell)
var2 = pybamm.Variable("var2", domain=whole_cell)
model.rhs = {var1: 0.1 * var1}
model.algebraic = {var2: 2 * var1 - var2}
model.initial_conditions = {var1: 1, var2: 2}
model.events = [
pybamm.Event("var1 = 1.5", pybamm.min(var1 - 1.5)),
pybamm.Event("var2 = 2.5", pybamm.min(var2 - 2.5)),
]
disc = get_discretisation_for_testing()
disc.process_model(model)
# Solve
solver = pybamm.ScikitsDaeSolver(rtol=1e-8,
atol=1e-8,
root_method="lm")
t_eval = np.linspace(0, 5, 100)
solution = solver.solve(model, t_eval)
np.testing.assert_array_less(solution.y[0], 1.5)
np.testing.assert_array_less(solution.y[-1], 2.5)
np.testing.assert_allclose(solution.y[0], np.exp(0.1 * solution.t))
np.testing.assert_allclose(solution.y[-1],
2 * np.exp(0.1 * solution.t))
def test_dae_integrate_bad_ics(self):
# Make sure that dae solver can fix bad ics automatically
# Constant
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
model = pybamm.BaseModel()
model.timescale_eval = 1
var = pybamm.Variable("var")
var2 = pybamm.Variable("var2")
model.rhs = {var: 0.5}
model.algebraic = {var2: 2 * var - var2}
model.initial_conditions = {var: 0, var2: 1}
disc = pybamm.Discretisation()
disc.process_model(model)
t_eval = np.linspace(0, 1, 100)
solver.set_up(model)
solver._set_initial_conditions(model, {}, True)
# check y0
np.testing.assert_array_equal(model.y0, [0, 0])
# check dae solutions
solution = solver.solve(model, t_eval)
np.testing.assert_array_equal(solution.t, t_eval)
np.testing.assert_allclose(0.5 * solution.t, solution.y[0])
np.testing.assert_allclose(1.0 * solution.t, solution.y[1])
def test_model_solver_dae_with_external(self):
# Create model
model = pybamm.BaseModel()
domain = ["negative electrode", "separator", "positive electrode"]
var1 = pybamm.Variable("var1", domain=domain)
var2 = pybamm.Variable("var2", domain=domain)
model.rhs = {var1: -var2}
model.initial_conditions = {var1: 1}
model.external_variables = [var2]
model.variables = {"var1": var1, "var2": var2}
# No need to set parameters; can use base discretisation (no spatial
# operators)
# create discretisation
mesh = get_mesh_for_testing()
spatial_methods = {"macroscale": pybamm.FiniteVolume()}
disc = pybamm.Discretisation(mesh, spatial_methods)
disc.process_model(model)
# Solve
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
t_eval = np.linspace(0, 10, 100)
solution = solver.solve(model,
t_eval,
external_variables={"var2": 0.5})
np.testing.assert_allclose(solution.y[0],
1 - 0.5 * solution.t,
rtol=1e-06)
def test_model_solver_dae(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.rhs = {var1: 0.1 * var1}
model.algebraic = {var2: 2 * var1 - var2}
model.initial_conditions = {var1: 1, var2: 2}
model.use_jacobian = False
disc = get_discretisation_for_testing()
disc.process_model(model)
# Solve
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
t_eval = np.linspace(0, 1, 100)
solution = solver.solve(model, t_eval)
np.testing.assert_array_equal(solution.t, t_eval)
np.testing.assert_allclose(solution.y[0], np.exp(0.1 * solution.t))
np.testing.assert_allclose(solution.y[-1],
2 * np.exp(0.1 * solution.t))
# Test time
self.assertGreater(solution.total_time,
solution.solve_time + solution.set_up_time)
def test_model_dae_integrate_failure_bad_ics(self):
# Force model to fail by providing bad ics
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
# Create custom model so that custom ics
class Model:
mass_matrix = pybamm.Matrix([[1.0, 0.0], [0.0, 0.0]])
y0 = np.array([0.0, 1.0])
terminate_events_eval = []
timescale_eval = 1
length_scales = {}
convert_to_format = "python"
def residuals_eval(self, t, y, ydot, inputs):
return np.array(
[0.5 * np.ones_like(y[0]) - ydot[0], 2 * y[0] - y[1]])
def jacobian_eval(self, t, y, inputs):
return np.array([[0.0, 0.0], [2.0, -1.0]])
model = Model()
t_eval = np.linspace(0, 1, 100)
with self.assertRaises(pybamm.SolverError):
solver._integrate(model, t_eval)
def test_model_step_events(self):
# Create model
model = pybamm.BaseModel()
var1 = pybamm.Variable("var1")
var2 = pybamm.Variable("var2")
model.rhs = {var1: 0.1 * var1}
model.algebraic = {var2: 2 * var1 - var2}
model.initial_conditions = {var1: 1, var2: 2}
model.events = [
pybamm.Event("var1 = 1.5", pybamm.min(var1 - 1.5)),
pybamm.Event("var2 = 2.5", pybamm.min(var2 - 2.5)),
]
disc = pybamm.Discretisation()
disc.process_model(model)
# Solve
step_solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
dt = 0.05
time = 0
end_time = 5
step_solution = None
while time < end_time:
step_solution = step_solver.step(step_solution,
model,
dt=dt,
npts=10)
time += dt
np.testing.assert_array_less(step_solution.y[0], 1.5)
np.testing.assert_array_less(step_solution.y[-1], 2.5001)
np.testing.assert_array_almost_equal(step_solution.y[0],
np.exp(0.1 * step_solution.t),
decimal=5)
np.testing.assert_array_almost_equal(step_solution.y[-1],
2 * np.exp(0.1 * step_solution.t),
decimal=5)
def test_dae_integrate_with_non_unity_mass(self):
# Constant
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
# Create custom model so that custom mass matrix can be used
class Model:
mass_matrix = pybamm.Matrix(np.array([[4.0, 0.0], [0.0, 0.0]]))
y0 = np.array([0.0, 0.0])
terminate_events_eval = []
timescale_eval = 1
convert_to_format = "python"
def residuals_eval(self, t, y, ydot, inputs):
return np.array([
0.5 * np.ones_like(y[0]) - 4 * ydot[0], 2.0 * y[0] - y[1]
])
def jacobian_eval(self, t, y, inputs):
return np.array([[0.0, 0.0], [2.0, -1.0]])
model = Model()
t_eval = np.linspace(0, 1, 100)
solution = solver._integrate(model, t_eval)
np.testing.assert_array_equal(solution.t, t_eval)
np.testing.assert_allclose(0.125 * solution.t, solution.y[0])
np.testing.assert_allclose(0.25 * solution.t, solution.y[1])
def test_model_solver_dae_events_casadi(self):
# Create model
model = pybamm.BaseModel()
for use_jacobian in [True, False]:
model.use_jacobian = use_jacobian
model.convert_to_format = "casadi"
whole_cell = [
"negative electrode", "separator", "positive electrode"
]
var1 = pybamm.Variable("var1", domain=whole_cell)
var2 = pybamm.Variable("var2", domain=whole_cell)
model.rhs = {var1: 0.1 * var1}
model.algebraic = {var2: 2 * var1 - var2}
model.initial_conditions = {var1: 1, var2: 2}
model.events = [
pybamm.Event("var1 = 1.5", pybamm.min(var1 - 1.5)),
pybamm.Event("var2 = 2.5", pybamm.min(var2 - 2.5)),
]
disc = get_discretisation_for_testing()
model_disc = disc.process_model(model, inplace=False)
# Solve
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
t_eval = np.linspace(0, 5, 100)
solution = solver.solve(model_disc, t_eval)
np.testing.assert_array_less(solution.y[0], 1.5)
np.testing.assert_array_less(solution.y[-1], 2.5)
np.testing.assert_allclose(solution.y[0], np.exp(0.1 * solution.t))
np.testing.assert_allclose(solution.y[-1],
2 * np.exp(0.1 * solution.t))
def test_dae_integrate_with_jacobian(self):
# Constant
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
def constant_growth_dae(t, y, ydot):
return np.array(
[0.5 * np.ones_like(y[0]) - ydot[0], 2.0 * y[0] - y[1]])
mass_matrix = np.array([[1.0, 0.0], [0.0, 0.0]])
def jacobian(t, y):
return np.array([[0.0, 0.0], [2.0, -1.0]])
y0 = np.array([0.0, 0.0])
t_eval = np.linspace(0, 1, 100)
solution = solver.integrate(constant_growth_dae,
y0,
t_eval,
mass_matrix=mass_matrix,
jacobian=jacobian)
np.testing.assert_array_equal(solution.t, t_eval)
np.testing.assert_allclose(0.5 * solution.t, solution.y[0])
np.testing.assert_allclose(1.0 * solution.t, solution.y[1])
# Nonlinear (tests when Jacobian a function of y)
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
def nonlinear_dae(t, y, ydot):
return np.array(
[0.5 * np.ones_like(y[0]) - ydot[0], 2 * y[0]**2 - y[1]])
mass_matrix = np.array([[1.0, 0.0], [0.0, 0.0]])
def jacobian(t, y):
return np.array([[0.0, 0.0], [4.0 * y[0], -1.0]])
y0 = np.array([0.0, 0.0])
t_eval = np.linspace(0, 1, 100)
solution = solver.integrate(nonlinear_dae,
y0,
t_eval,
mass_matrix=mass_matrix,
jacobian=jacobian)
np.testing.assert_array_equal(solution.t, t_eval)
np.testing.assert_allclose(0.5 * solution.t, solution.y[0])
np.testing.assert_allclose(0.5 * solution.t**2, solution.y[1])
def default_solver(self):
"""
Create and return the default solver for this model
"""
if (self.options["current collector"] != "uniform"
or self.options["surface form"] == "algebraic"):
return pybamm.ScikitsDaeSolver()
else:
return pybamm.ScipySolver()
def default_solver(self):
"""
Create and return the default solver for this model
"""
# Different solver depending on whether we solve ODEs or DAEs
if (self.options["surface form"] == "differential"
and self.options["current collector"] == "uniform"):
return pybamm.ScipySolver()
else:
return pybamm.ScikitsDaeSolver()
def test_dae_integrate_failure(self):
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
def constant_growth_dae(t, y, ydot):
return [0.5 * np.ones_like(y[0]) - ydot[0], 2 * y[0] - y[1]]
y0 = np.array([0, 1])
t_eval = np.linspace(0, 1, 100)
with self.assertRaises(pybamm.SolverError):
solver.integrate(constant_growth_dae, y0, t_eval)
def default_solver(self):
"""
Create and return the default solver for this model
"""
# Different solver depending on whether we solve ODEs or DAEs
dimensionality = self.options["dimensionality"]
if dimensionality == 0:
return pybamm.ScipySolver()
else:
return pybamm.ScikitsDaeSolver()
def default_solver(self):
"""
Return default solver based on whether model is ODE model or DAE model.
There are bugs with KLU on the lead-acid models.
"""
if len(self.algebraic) == 0:
return pybamm.ScipySolver()
elif pybamm.have_scikits_odes():
return pybamm.ScikitsDaeSolver()
else: # pragma: no cover
return pybamm.CasadiSolver(mode="safe")
def test_dae_solver_algebraic_model(self):
model = pybamm.BaseModel()
var = pybamm.Variable("var")
model.algebraic = {var: var + 1}
model.initial_conditions = {var: 0}
disc = pybamm.Discretisation()
disc.process_model(model)
solver = pybamm.ScikitsDaeSolver()
t_eval = np.linspace(0, 1)
solution = solver.solve(model, t_eval)
np.testing.assert_array_equal(solution.y, -1)
def test_dae_integrate_bad_ics(self):
# Constant
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
def constant_growth_dae(t, y, ydot):
return [0.5 * np.ones_like(y[0]) - ydot[0], 2 * y[0] - y[1]]
def constant_growth_dae_rhs(t, y):
return np.array([constant_growth_dae(t, y, [0])[0]])
def constant_growth_dae_algebraic(t, y):
return np.array([constant_growth_dae(t, y, [0])[1]])
y0_guess = np.array([0, 1])
t_eval = np.linspace(0, 1, 100)
y0 = solver.calculate_consistent_initial_conditions(
constant_growth_dae_rhs, constant_growth_dae_algebraic, y0_guess)
# check y0
np.testing.assert_array_equal(y0, [0, 0])
# check dae solutions
solution = solver.integrate(constant_growth_dae, y0, t_eval)
np.testing.assert_array_equal(solution.t, t_eval)
np.testing.assert_allclose(0.5 * solution.t, solution.y[0])
np.testing.assert_allclose(1.0 * solution.t, solution.y[1])
# Exponential decay
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
def exponential_decay_dae(t, y, ydot):
return [-0.1 * y[0] - ydot[0], 2 * y[0] - y[1]]
y0 = np.array([1, 2])
t_eval = np.linspace(0, 1, 100)
solution = solver.integrate(exponential_decay_dae, y0, t_eval)
np.testing.assert_allclose(solution.y[0], np.exp(-0.1 * solution.t))
np.testing.assert_allclose(solution.y[1],
2 * np.exp(-0.1 * solution.t))
def test_solve_ode_model_with_dae_solver_casadi(self):
model = pybamm.BaseModel()
model.convert_to_format = "casadi"
var = pybamm.Variable("var")
model.rhs = {var: 0.1 * var}
model.initial_conditions = {var: 1}
disc = get_discretisation_for_testing()
disc.process_model(model)
# Solve
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
t_eval = np.linspace(0, 1, 100)
solution = solver.solve(model, t_eval)
np.testing.assert_array_equal(solution.t, t_eval)
np.testing.assert_allclose(solution.y[0], np.exp(0.1 * solution.t))
def test_model_step_nonsmooth_events(self):
# Create model
model = pybamm.BaseModel()
model.timescale = pybamm.Scalar(1)
var1 = pybamm.Variable("var1")
var2 = pybamm.Variable("var2")
a = 0.6
discontinuities = (np.arange(3) + 1) * a
model.rhs = {var1: pybamm.Modulo(pybamm.t * model.timescale, a)}
model.algebraic = {var2: 2 * var1 - var2}
model.initial_conditions = {var1: 0, var2: 0}
model.events = [
pybamm.Event("var1 = 0.55", pybamm.min(var1 - 0.55)),
pybamm.Event("var2 = 1.2", pybamm.min(var2 - 1.2)),
]
for discontinuity in discontinuities:
model.events.append(
pybamm.Event("nonsmooth rate", pybamm.Scalar(discontinuity)))
disc = get_discretisation_for_testing()
disc.process_model(model)
# Solve
step_solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
dt = 0.05
time = 0
end_time = 3
step_solution = None
while time < end_time:
step_solution = step_solver.step(step_solution,
model,
dt=dt,
npts=10)
time += dt
np.testing.assert_array_less(step_solution.y[0, :-1], 0.55)
np.testing.assert_array_less(step_solution.y[-1, :-1], 1.2)
np.testing.assert_equal(step_solution.t_event[0], step_solution.t[-1])
np.testing.assert_array_equal(step_solution.y_event[:, 0],
step_solution.y[:, -1])
var1_soln = (step_solution.t %
a)**2 / 2 + a**2 / 2 * (step_solution.t // a)
var2_soln = 2 * var1_soln
np.testing.assert_array_almost_equal(step_solution.y[0],
var1_soln,
decimal=5)
np.testing.assert_array_almost_equal(step_solution.y[-1],
var2_soln,
decimal=5)
def test_model_solver_dae_inputs_in_initial_conditions(self):
# Create model
model = pybamm.BaseModel()
var1 = pybamm.Variable("var1")
var2 = pybamm.Variable("var2")
model.rhs = {var1: pybamm.InputParameter("rate") * var1}
model.algebraic = {var2: var1 - var2}
model.initial_conditions = {
var1: pybamm.InputParameter("ic 1"),
var2: pybamm.InputParameter("ic 2"),
}
# Solve
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
t_eval = np.linspace(0, 5, 100)
solution = solver.solve(model,
t_eval,
inputs={
"rate": -1,
"ic 1": 0.1,
"ic 2": 2
})
np.testing.assert_array_almost_equal(solution.y[0],
0.1 * np.exp(-solution.t),
decimal=5)
np.testing.assert_array_almost_equal(solution.y[-1],
0.1 * np.exp(-solution.t),
decimal=5)
# Solve again with different initial conditions
solution = solver.solve(model,
t_eval,
inputs={
"rate": -0.1,
"ic 1": 1,
"ic 2": 3
})
np.testing.assert_array_almost_equal(solution.y[0],
1 * np.exp(-0.1 * solution.t),
decimal=5)
np.testing.assert_array_almost_equal(solution.y[-1],
1 * np.exp(-0.1 * solution.t),
decimal=5)
def test_dae_integrate_with_non_unity_mass(self):
# Constant
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
def constant_growth_dae(t, y, ydot):
return np.array(
[0.5 * np.ones_like(y[0]) - 4 * ydot[0], 2.0 * y[0] - y[1]])
mass_matrix = np.array([[4.0, 0.0], [0.0, 0.0]])
def jacobian(t, y):
return np.array([[0.0, 0.0], [2.0, -1.0]])
y0 = np.array([0.0, 0.0])
t_eval = np.linspace(0, 1, 100)
solution = solver.integrate(constant_growth_dae,
y0,
t_eval,
mass_matrix=mass_matrix,
jacobian=jacobian)
np.testing.assert_array_equal(solution.t, t_eval)
np.testing.assert_allclose(0.125 * solution.t, solution.y[0])
np.testing.assert_allclose(0.25 * solution.t, solution.y[1])
def test_model_solver_dae_no_nonsmooth_python(self):
model = pybamm.BaseModel()
model.convert_to_format = "python"
whole_cell = ["negative electrode", "separator", "positive electrode"]
var1 = pybamm.Variable("var1", domain=whole_cell)
var2 = pybamm.Variable("var2", domain=whole_cell)
discontinuity = 5.6
def nonsmooth_rate(t):
return 0.1 * int(t < discontinuity) + 0.1
def nonsmooth_mult(t):
return int(t < discontinuity) + 1.0
# put in an extra heaviside with no time dependence, this should be ignored by
# the solver i.e. no extra discontinuities added
model.rhs = {var1: 0.1 * var1}
model.algebraic = {var2: 2 * var1 - var2}
model.initial_conditions = {var1: 1, var2: 2}
disc = get_discretisation_for_testing()
disc.process_model(model)
# Solve
solver = pybamm.ScikitsDaeSolver(rtol=1e-9,
atol=1e-9,
root_method="lm")
# create two time series, one without a time point on the discontinuity,
# and one with
t_eval = np.linspace(0, 5, 10)
solution = solver.solve(model, t_eval)
# test solution, discontinuity should not be triggered
np.testing.assert_array_equal(solution.t, t_eval)
np.testing.assert_allclose(solution.y[0], np.exp(0.1 * solution.t))
np.testing.assert_allclose(solution.y[-1],
2 * np.exp(0.1 * solution.t))
def test_model_solver_dae_nonsmooth(self):
whole_cell = ["negative electrode", "separator", "positive electrode"]
var1 = pybamm.Variable("var1", domain=whole_cell)
var2 = pybamm.Variable("var2")
discontinuity = 0.6
# Create three different models with the same solution, each expressing the
# discontinuity in a different way
# first model explicitly adds a discontinuity event
def nonsmooth_rate(t):
return 0.1 * (t < discontinuity) + 0.1
rate = pybamm.Function(nonsmooth_rate, pybamm.t)
model1 = pybamm.BaseModel()
model1.rhs = {var1: rate * var1}
model1.algebraic = {var2: var2}
model1.initial_conditions = {var1: 1, var2: 0}
model1.events = [
pybamm.Event("var1 = 1.5", pybamm.min(var1 - 1.5)),
pybamm.Event(
"nonsmooth rate",
pybamm.Scalar(discontinuity),
pybamm.EventType.DISCONTINUITY,
),
]
# second model implicitly adds a discontinuity event via a heaviside function
model2 = pybamm.BaseModel()
model2.rhs = {var1: (0.1 * (pybamm.t < discontinuity) + 0.1) * var1}
model2.algebraic = {var2: var2}
model2.initial_conditions = {var1: 1, var2: 0}
model2.events = [pybamm.Event("var1 = 1.5", pybamm.min(var1 - 1.5))]
# third model implicitly adds a discontinuity event via another heaviside
# function
model3 = pybamm.BaseModel()
model3.rhs = {var1: (-0.1 * (discontinuity < pybamm.t) + 0.2) * var1}
model3.algebraic = {var2: var2}
model3.initial_conditions = {var1: 1, var2: 0}
model3.events = [pybamm.Event("var1 = 1.5", pybamm.min(var1 - 1.5))]
for model in [model1, model2, model3]:
disc = get_discretisation_for_testing()
disc.process_model(model)
# Solve
solver = pybamm.ScikitsDaeSolver(rtol=1e-8, atol=1e-8)
# create two time series, one without a time point on the discontinuity,
# and one with
t_eval1 = np.linspace(0, 5, 10)
t_eval2 = np.insert(t_eval1,
np.searchsorted(t_eval1,
discontinuity), discontinuity)
solution1 = solver.solve(model, t_eval1)
solution2 = solver.solve(model, t_eval2)
# check time vectors
for solution in [solution1, solution2]:
# time vectors are ordered
self.assertTrue(np.all(solution.t[:-1] <= solution.t[1:]))
# time value before and after discontinuity is an epsilon away
dindex = np.searchsorted(solution.t, discontinuity)
value_before = solution.t[dindex - 1]
value_after = solution.t[dindex]
self.assertEqual(value_before + sys.float_info.epsilon,
discontinuity)
self.assertEqual(value_after - sys.float_info.epsilon,
discontinuity)
# both solution time vectors should have same number of points
self.assertEqual(len(solution1.t), len(solution2.t))
# check solution
for solution in [solution1, solution2]:
np.testing.assert_array_less(solution.y[0], 1.5)
np.testing.assert_array_less(solution.y[-1], 2.5)
var1_soln = np.exp(0.2 * solution.t)
y0 = np.exp(0.2 * discontinuity)
var1_soln[solution.t > discontinuity] = y0 * np.exp(
0.1 *
(solution.t[solution.t > discontinuity] - discontinuity))
np.testing.assert_allclose(solution.y[0],
var1_soln,
rtol=1e-06)
def test_model_solver_dae_nonsmooth_python(self):
model = pybamm.BaseModel()
model.convert_to_format = "python"
whole_cell = ["negative electrode", "separator", "positive electrode"]
var1 = pybamm.Variable("var1", domain=whole_cell)
var2 = pybamm.Variable("var2", domain=whole_cell)
discontinuity = 0.6
def nonsmooth_rate(t):
return 0.1 * int(t < discontinuity) + 0.1
def nonsmooth_mult(t):
return int(t < discontinuity) + 1.0
rate = pybamm.Function(nonsmooth_rate, pybamm.t)
mult = pybamm.Function(nonsmooth_mult, pybamm.t)
# put in an extra heaviside with no time dependence, this should be ignored by
# the solver i.e. no extra discontinuities added
model.rhs = {var1: rate * var1 + (var1 < 0)}
model.algebraic = {var2: mult * var1 - var2}
model.initial_conditions = {var1: 1, var2: 2}
model.events = [
pybamm.Event("var1 = 1.5", pybamm.min(var1 - 1.5)),
pybamm.Event("var2 = 2.5", pybamm.min(var2 - 2.5)),
pybamm.Event(
"nonsmooth rate",
pybamm.Scalar(discontinuity),
pybamm.EventType.DISCONTINUITY,
),
pybamm.Event(
"nonsmooth mult",
pybamm.Scalar(discontinuity),
pybamm.EventType.DISCONTINUITY,
),
]
disc = get_discretisation_for_testing()
disc.process_model(model)
# Solve
solver = pybamm.ScikitsDaeSolver(rtol=1e-8,
atol=1e-8,
root_method="lm")
# create two time series, one without a time point on the discontinuity,
# and one with
t_eval1 = np.linspace(0, 5, 10)
t_eval2 = np.insert(t_eval1, np.searchsorted(t_eval1, discontinuity),
discontinuity)
solution1 = solver.solve(model, t_eval1)
solution2 = solver.solve(model, t_eval2)
# check time vectors
for solution in [solution1, solution2]:
# time vectors are ordered
self.assertTrue(np.all(solution.t[:-1] <= solution.t[1:]))
# time value before and after discontinuity is an epsilon away
dindex = np.searchsorted(solution.t, discontinuity)
value_before = solution.t[dindex - 1]
value_after = solution.t[dindex]
self.assertEqual(value_before + sys.float_info.epsilon,
discontinuity)
self.assertEqual(value_after - sys.float_info.epsilon,
discontinuity)
# both solution time vectors should have same number of points
self.assertEqual(len(solution1.t), len(solution2.t))
# check solution
for solution in [solution1, solution2]:
np.testing.assert_array_less(solution.y[0], 1.5)
np.testing.assert_array_less(solution.y[-1], 2.5)
var1_soln = np.exp(0.2 * solution.t)
y0 = np.exp(0.2 * discontinuity)
var1_soln[solution.t > discontinuity] = y0 * np.exp(
0.1 * (solution.t[solution.t > discontinuity] - discontinuity))
var2_soln = 2 * var1_soln
var2_soln[solution.t > discontinuity] = var1_soln[
solution.t > discontinuity]
np.testing.assert_allclose(solution.y[0], var1_soln, rtol=1e-06)
np.testing.assert_allclose(solution.y[-1], var2_soln, rtol=1e-06)
