Default solver from Casadi to IDAKLU

pybop/models/base_model.py

@@ -318,6 +318,14 @@ def set_up_for_eis(self, model):
         model : pybamm.Model
             The PyBaMM model to be used for EIS simulations.
         """
+        if not isinstance(self._solver, pybamm.CasadiSolver):
+            print(
+                "CasadiSolver is required for EIS predictions, the solver has been changed."
+            )
+            self._solver = pybamm.CasadiSolver(
+                atol=self._solver.atol, rtol=self._solver.rtol
+            )
+
         V_cell = pybamm.Variable("Voltage variable [V]")
         model.variables["Voltage variable [V]"] = V_cell
         V = model.variables["Voltage [V]"]

pybop/models/empirical/base_ecm.py

@@ -84,7 +84,7 @@ def __init__(
         self._spatial_methods = (
             spatial_methods or self.pybamm_model.default_spatial_methods
         )
-        self._solver = solver or self.pybamm_model.default_solver
+        self._solver = solver or pybamm.IDAKLUSolver()
 
         # Internal attributes for the built model are initialized but not set
         self._model_with_set_params = None

pybop/models/lithium_ion/base_echem.py

@@ -2,6 +2,7 @@
 import warnings
 from typing import Optional
 
+import pybamm
 from pybamm import lithium_ion as pybamm_lithium_ion
 
 from pybop.models.base_model import BaseModel, Inputs
@@ -72,9 +73,7 @@ def __init__(
             spatial_methods or self.pybamm_model.default_spatial_methods
         )
         if solver is None:
-            self._solver = self.pybamm_model.default_solver
-            self._solver.mode = "fast with events"
-            self._solver.max_step_decrease_count = 1
+            self._solver = pybamm.IDAKLUSolver(atol=1e-5, rtol=1e-5)
         else:
             self._solver = solver
 

tests/integration/test_model_experiment_changes.py

@@ -1,4 +1,5 @@
 import numpy as np
+import pybamm
 import pytest
 
 import pybop
@@ -34,14 +35,18 @@ class TestModelAndExperimentChanges:
     def parameters(self, request):
         return request.param
 
+    @pytest.fixture
+    def solver(self):
+        return pybamm.IDAKLUSolver(atol=1e-6, rtol=1e-6)
+
     @pytest.mark.integration
-    def test_changing_experiment(self, parameters):
+    def test_changing_experiment(self, parameters, solver):
         # Change the experiment and check that the results are different.
 
         parameter_set = pybop.ParameterSet.pybamm("Chen2020")
         parameter_set.update(parameters.as_dict("true"))
         initial_state = {"Initial SoC": 0.5}
-        model = pybop.lithium_ion.SPM(parameter_set=parameter_set)
+        model = pybop.lithium_ion.SPM(parameter_set=parameter_set, solver=solver)
 
         t_eval = np.arange(0, 3600, 2)  # Default 1C discharge to cut-off voltage
         solution_1 = model.predict(initial_state=initial_state, t_eval=t_eval)
@@ -66,19 +71,19 @@ def test_changing_experiment(self, parameters):
         np.testing.assert_allclose(cost_2, 0, atol=1e-5)
 
     @pytest.mark.integration
-    def test_changing_model(self, parameters):
+    def test_changing_model(self, parameters, solver):
         # Change the model and check that the results are different.
 
         parameter_set = pybop.ParameterSet.pybamm("Chen2020")
         parameter_set.update(parameters.as_dict("true"))
         initial_state = {"Initial SoC": 0.5}
         experiment = pybop.Experiment(["Charge at 1C until 4.1 V (2 seconds period)"])
 
-        model = pybop.lithium_ion.SPM(parameter_set=parameter_set)
+        model = pybop.lithium_ion.SPM(parameter_set=parameter_set, solver=solver)
         solution_1 = model.predict(initial_state=initial_state, experiment=experiment)
         cost_1 = self.final_cost(solution_1, model, parameters)
 
-        model = pybop.lithium_ion.SPMe(parameter_set=parameter_set)
+        model = pybop.lithium_ion.SPMe(parameter_set=parameter_set, solver=solver)
         solution_2 = model.predict(initial_state=initial_state, experiment=experiment)
         cost_2 = self.final_cost(solution_2, model, parameters)
 
@@ -109,7 +114,7 @@ def final_cost(self, solution, model, parameters):
         return results.final_cost
 
     @pytest.mark.integration
-    def test_multi_fitting_problem(self):
+    def test_multi_fitting_problem(self, solver):
         parameter_set = pybop.ParameterSet.pybamm("Chen2020")
         parameters = pybop.Parameter(
             "Negative electrode active material volume fraction",
@@ -119,7 +124,7 @@ def test_multi_fitting_problem(self):
             ],
         )
 
-        model_1 = pybop.lithium_ion.SPM(parameter_set=parameter_set)
+        model_1 = pybop.lithium_ion.SPM(parameter_set=parameter_set, solver=solver)
         experiment_1 = pybop.Experiment(
             ["Discharge at 1C until 3 V (4 seconds period)"]
         )
@@ -132,7 +137,9 @@ def test_multi_fitting_problem(self):
             }
         )
 
-        model_2 = pybop.lithium_ion.SPMe(parameter_set=parameter_set.copy())
+        model_2 = pybop.lithium_ion.SPMe(
+            parameter_set=parameter_set.copy(), solver=solver
+        )
         experiment_2 = pybop.Experiment(
             ["Discharge at 3C until 3 V (4 seconds period)"]
         )

tests/unit/test_posterior.py

@@ -1,4 +1,5 @@
 import numpy as np
+import pybamm
 import pytest
 import scipy.stats as st
 
@@ -12,7 +13,7 @@ class TestLogPosterior:
 
     @pytest.fixture
     def model(self):
-        return pybop.lithium_ion.SPM()
+        return pybop.lithium_ion.SPM(solver=pybamm.IDAKLUSolver(atol=1e-6, rtol=1e-6))
 
     @pytest.fixture
     def ground_truth(self):