irksome.ufl package

Submodules

irksome.ufl.deriv module

irksome.ufl.deriv.Dt(f, order=1)

Short-hand function to produce a TimeDerivative of a given order.

exception irksome.ufl.deriv.IrksomeImportOrderException

Bases: Exception

class irksome.ufl.deriv.TimeDerivative(f)

Bases: Derivative

UFL node representing a time derivative of some quantity/field. Note: Currently form compilers do not understand how to process these nodes. Instead, Irksome pre-processes forms containing TimeDerivative nodes.

Initalise.

property ufl_free_indices

property ufl_index_dimensions

property ufl_shape

class irksome.ufl.deriv.TimeDerivativeRuleDispatcher(t=None, timedep_coeffs=None, **kwargs)

Bases: DAGTraverser

Mapping rules to splat out time derivatives so that replacement should work on more complex problems.

Initialise.

process(o)

process(o: TimeDerivative)

process(o: BaseForm)

process(o: Expr)

Process node by type.

Args:

o:

UFL expression to start DAG traversal from.

**kwargs:

Keyword arguments for the process singledispatchmethod.

Returns:

Processed Expr.

time_derivative(o)

class irksome.ufl.deriv.TimeDerivativeRuleset(t=None, timedep_coeffs=None)

Bases: GenericDerivativeRuleset

Apply AD rules to time derivative expressions.

Initialise.

constant(o)

process(o)

process(o: ConstantValue)

process(o: SpatialCoordinate)

process(o: Coefficient)

process(o: TimeDerivative, f)

process(o: Variable, *operands)

process(o: ReferenceValue, *operands)

process(o: ReferenceGrad, *operands)

process(o: Indexed, *operands)

process(o: Grad, *operands)

process(o: Div, *operands)

process(o: Derivative, *operands)

process(o: Curl, *operands)

process(o: Conj, *operands)

Process o.

Args:

o: Expr to be processed.

Returns:

Processed object.

terminal(o)

terminal_modifier(o, *operands)

time_derivative(o, f)

irksome.ufl.deriv.apply_time_derivatives(expression, t=None, timedep_coeffs=None)

irksome.ufl.deriv.check_irksome_import_order()

Check that irksome has been imported early enough.

Due to the inadequacies of the UFL type system, it is not possible to define a new UFL type once any ufl MultiFunction has been used.

This restriction can be removed once all MultiFunctions have been transitioned to ufl.corealg.dag_traverser.DAGTraverser.

irksome.ufl.deriv.expand_time_derivatives(expression, t=None, timedep_coeffs=None)

irksome.ufl.estimate_degrees module

class irksome.ufl.estimate_degrees.TimeDegreeEstimator(degree_mapping=None, **kwargs)

Bases: DAGTraverser

Time degree estimator.

This algorithm is exact for a few operators and heuristic for many.

Initialise.

add_degrees(v, *ops)

conditional(v, c, *ops)

form(o)

formsum(o)

integral(o)

interpolate(o)

math_function(v, a)

Apply to math_function.

Using the heuristic: degree(sin(const)) == 0 degree(sin(a)) == degree(a)+2 which can be wildly inaccurate but at least gives a somewhat high integration degree.

max_degree(v, *ops)

minmax(v, *ops)

non_numeric(v, *args)

not_handled(v, *ops)

power(v, a, b)

Apply to power.

If b is a positive integer: degree(a**b) == degree(a)*b otherwise use the heuristic: degree(a**b) == degree(a) + 2.

process(o)

process(o: FormSum)

process(o: Interpolate)

process(o: Form)

process(o: Integral)

process(o: SpatialCoordinate)

process(o: ConstantValue)

process(o: Coefficient)

process(o: Cofunction)

process(o: Argument)

process(o: TimeDerivative, degree)

process(o: IndexSum, degree, *ops)

process(o: ComponentTensor, degree, *ops)

process(o: Variable, degree, *ops)

process(o: ReferenceValue, degree, *ops)

process(o: ReferenceGrad, degree, *ops)

process(o: Indexed, degree, *ops)

process(o: Grad, degree, *ops)

process(o: Div, degree, *ops)

process(o: Derivative, degree, *ops)

process(o: Curl, degree, *ops)

process(o: Conj, degree, *ops)

process(o: Abs, degree, *ops)

process(v: Inverse, *ops)

process(v: Determinant, *ops)

process(v: Transposed, *ops)

process(v: Trace, *ops)

process(v: Sym, *ops)

process(v: Skew, *ops)

process(v: Cofactor, *ops)

process(v: ExprMapping, *ops)

process(v: ExprList, *ops)

process(v: ListTensor, *ops)

process(v: Sum, *ops)

process(v: Cross, *ops)

process(v: Outer, *ops)

process(v: Dot, *ops)

process(v: Inner, *ops)

process(v: Product, *ops)

process(v: Division, *ops)

process(v: Power, a, b)

process(v: MathFunction, a)

process(v: Conditional, c, *ops)

process(v: MaxValue, *ops)

process(v: MinValue, *ops)

process(v: MultiIndex, *args)

process(v: Condition, *args)

process(v: Label, *args)

Process node by type.

Args:

o:

UFL expression to start DAG traversal from.

**kwargs:

Keyword arguments for the process singledispatchmethod.

Returns:

Processed Expr.

terminal(o)

terminal_modifier(o, degree, *ops)

time_derivative(o, degree)

irksome.ufl.estimate_degrees.estimate_time_degree(expression, test_degree, trial_degree, t=None, timedep_coeffs=None)

irksome.ufl.estimate_degrees.get_degree_mapping(expression, test_degree, trial_degree, t=None, timedep_coeffs=None)

Map time-dependent terminals to their polynomial degree.

Parameters:

• expression – a ufl.BaseForm or ufl.Expr.

• test_degree – the temporal polynomial degree of the test space.

• trial_degree – the temporal polynomial degree of the trial space.

• t – the time variable as a Constant or Function in the Real space.

• timedep_coeffs – a list of Function that depend on time.

Returns:

a dict mapping time-dependent terminals to their degree in time.

irksome.ufl.manipulation module

Manipulation of expressions containing TimeDerivative terms.

These can be used to do some basic checking of the suitability of a Form for use in Irksome (via check_integrals), and splitting out terms in the Form that contain a time derivative from those that don’t (via split_time_derivative_terms).

class irksome.ufl.manipulation.SplitTimeForm(time: BaseForm, remainder: BaseForm)

Bases: NamedTuple

A container for a form split into time terms and a remainder.

Create new instance of SplitTimeForm(time, remainder)

remainder: BaseForm

Alias for field number 1

time: BaseForm

Alias for field number 0

irksome.ufl.manipulation.check_integrals(integrals: Sequence[Integral], t: Expr = None, timedep_coeffs: Sequence[Coefficient] = (), expect_time_derivative: bool = True)

Check a list of integrals for linearity in the time derivative.

Parameters:

• integrals – list of integrals.

• timedep_coeffs – The time-dependent coefficients.

• expect_time_derivative – Are we expecting to see a time derivative?

Raises:

ValueError – if we are expecting a time derivative and don’t see one, or time derivatives are applied nonlinearly, to more than one coefficient, or more than first order.

irksome.ufl.manipulation.remove_time_derivatives(F: Form)

Helper function to strip all time derivatives from a Form

irksome.ufl.manipulation.split_time_derivative_terms(form: BaseForm, t: Expr = None, timedep_coeffs: Sequence[Coefficient] = ()) → SplitTimeForm

Split terms from a Form.

This splits a form (a sum of integrals) into those integrals which do contain a TimeDerivative acting on timedep_coeffs and those that don’t.

Parameters:

• form – The form to split.

• t – The time variable.

• timedep_coeffs – The time-dependent coefficients.

Returns:

a SplitTimeForm tuple.

Raises:

ValueError – if the form does not apply anything other than first-order time derivatives to a single coefficient.

Module contents