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#1507 remove algebraic equation check #1510

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Jun 14, 2021
Merged

#1507 remove algebraic equation check #1510

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53a1942
#1507 remove algebraic equation check
rtimms Jun 11, 2021
e133009
#1507 changelog
rtimms Jun 12, 2021
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36 changes: 8 additions & 28 deletions pybamm/models/base_model.py
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Original file line number Diff line number Diff line change
Expand Up @@ -639,40 +639,20 @@ def check_well_determined(self, post_discretisation):

def check_algebraic_equations(self, post_discretisation):
"""
Check that the algebraic equations are well-posed.
Before discretisation, each algebraic equation key must appear in the equation
After discretisation, there must be at least one StateVector in each algebraic
equation
Check that the algebraic equations are well-posed. After discretisation,
there must be at least one StateVector in each algebraic equation.
"""
vars_in_bcs = set()
unpacker = pybamm.SymbolUnpacker(pybamm.Variable)
for side_eqn in self.boundary_conditions.values():
all_vars = unpacker.unpack_list_of_symbols(
[eqn for eqn, _ in side_eqn.values()]
)
vars_in_bcs.update(all_vars.keys())
if not post_discretisation:
# After the model has been defined, each algebraic equation key should
# appear in that algebraic equation, or in the boundary conditions
# this has been relaxed for concatenations for now
for var, eqn in self.algebraic.items():
if not (
any(x.id == var.id for x in eqn.pre_order())
or var.id in vars_in_bcs
or isinstance(var, pybamm.Concatenation)
):
raise pybamm.ModelError(
"each variable in the algebraic eqn keys must appear in the eqn"
)
else:
# variables in keys don't get discretised so they will no longer match
# with the state vectors in the algebraic equations. Instead, we check
# that each algebraic equation contains some StateVector
if post_discretisation:
# Check that each algebraic equation contains some StateVector
for eqn in self.algebraic.values():
if not eqn.has_symbol_of_classes(pybamm.StateVector):
raise pybamm.ModelError(
"each algebraic equation must contain at least one StateVector"
)
else:
# We do not perfom any checks before discretisation (most problematic
# cases should be caught by `check_well_determined`)
pass

def check_ics_bcs(self):
"""Check that the initial and boundary conditions are well-posed."""
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12 changes: 0 additions & 12 deletions tests/unit/test_models/test_base_model.py
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Expand Up @@ -342,18 +342,6 @@ def test_check_well_posedness_variables(self):
with self.assertRaisesRegex(pybamm.ModelError, "extra algebraic keys"):
model.check_well_posedness()

# before discretisation, fail if the algebraic eqn keys don't appear in the eqns
model = pybamm.BaseModel()
model.algebraic = {c: d - 2, d: d - c}
with self.assertRaisesRegex(
pybamm.ModelError,
"each variable in the algebraic eqn keys must appear in the eqn",
):
model.check_well_posedness()
# passes when we switch the equations around
model.algebraic = {c: d - c, d: d - 2}
model.check_well_posedness()

# after discretisation, algebraic equation without a StateVector fails
model = pybamm.BaseModel()
model.algebraic = {
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