#920 raise error if timescale depends on inputs

pybamm/solvers/base_solver.py

@@ -163,7 +163,13 @@ def set_up(self, model, inputs=None):
         inputs = inputs or {}
 
         # Set model timescale
-        model.timescale_eval = model.timescale.evaluate(inputs=inputs)
+        try:
+            model.timescale_eval = model.timescale.evaluate()
+        except KeyError as e:
+            raise pybamm.SolverError(
+                "The model timescale is a function of an input parameter "
+                "(original error: {})".format(e)
+            )
 
         if (
             isinstance(self, (pybamm.CasadiSolver, pybamm.CasadiAlgebraicSolver))

pybamm/solvers/processed_variable.py

@@ -59,12 +59,8 @@ def __init__(self, base_variable, solution, known_evals=None, warn=True):
         self.known_evals = known_evals
         self.warn = warn
 
-        # Set timescale -- used evaluated timescale if available (to account
-        # for inputs set during solve)
-        try:
-            self.timescale = solution.model.timescale_eval
-        except AttributeError:
-            self.timescale = solution.model.timescale.evaluate()
+        # Set timescale
+        self.timescale = solution.model.timescale.evaluate()
         self.t_pts = self.t_sol * self.timescale
 
         # Store spatial variables to get scales
@@ -498,7 +494,7 @@ def get_spatial_scale(self, name, domain=None):
             if self.warn:
                 pybamm.logger.warning(
                     "No scale set for spatial variable {}. "
-                    "Using default of 1 [m]".format(name)
+                    "Using default of 1 [m].".format(name)
                 )
             scale = 1
         return scale

tests/integration/test_solvers/test_external_variables.py

@@ -13,10 +13,10 @@ def test_on_dfn(self):
         model = pybamm.lithium_ion.DFN()
         geometry = model.default_geometry
         param = model.default_parameter_values
-        param.update({"Electrode height [m]": "[input]"})
+        param.update({"Negative electrode conductivity [S.m-1]": "[input]"})
         param.process_model(model)
         param.process_geometry(geometry)
-        inputs = {"Electrode height [m]": e_height}
+        inputs = {"Negative electrode conductivity [S.m-1]": e_height}
         var = pybamm.standard_spatial_vars
         var_pts = {var.x_n: 5, var.x_s: 5, var.x_p: 5, var.r_n: 10, var.r_p: 10}
         spatial_methods = model.default_spatial_methods

tests/unit/test_solvers/test_base_solver.py

@@ -264,6 +264,18 @@ def test_convert_to_casadi_format(self):
         self.assertEqual(model.convert_to_format, "casadi")
         pybamm.set_logging_level("WARNING")
 
+    def test_timescale_input_fail(self):
+        # Make sure timescale can't depend on inputs
+        model = pybamm.BaseModel()
+        v = pybamm.Variable("v")
+        model.rhs = {v: -1}
+        model.initial_conditions = {v: 1}
+        a = pybamm.InputParameter("a")
+        model.timescale = a
+        solver = pybamm.BaseSolver()
+        with self.assertRaisesRegex(pybamm.SolverError, "The model timescale"):
+            solver.set_up(model, inputs={"a": 10})
+
 
 if __name__ == "__main__":
     print("Add -v for more debug output")

tests/unit/test_solvers/test_solution.py

@@ -148,7 +148,7 @@ def test_solution_evals_with_inputs(self):
         model = pybamm.lithium_ion.SPM()
         geometry = model.default_geometry
         param = model.default_parameter_values
-        param.update({"Electrode height [m]": "[input]"})
+        param.update({"Negative electrode conductivity [S.m-1]": "[input]"})
         param.process_model(model)
         param.process_geometry(geometry)
         var = pybamm.standard_spatial_vars
@@ -163,7 +163,7 @@ def test_solution_evals_with_inputs(self):
             spatial_methods=spatial_methods,
             solver=solver,
         )
-        inputs = {"Electrode height [m]": 0.1}
+        inputs = {"Negative electrode conductivity [S.m-1]": 0.1}
         sim.solve(t_eval=np.linspace(0, 10, 10), inputs=inputs)
         time = sim.solution["Time [h]"](sim.solution.t)
         self.assertEqual(len(time), 10)