zoomy_core.model.derivation.operations

Derivation operations that do more than a substitution: SolveFor, SolveLinearSystem, ChangeOfVariables. They follow the Operation protocol of zoomy_core.model.operations and act on a Model before it is lifted to a SystemModel.

Module Contents

Classes

SolveFor	Reorient an equation in place into variable = solution. Pipeline counterpart of equation.solve_for(var), which returns a new equation.
SolveLinearSystem	Solve a coupled linear system A v = b for a family of variables with sympy.linsolve. solve() returns an indexable MomentFamily of oriented rows v_i = solution_i that can be passed to .apply.
Granularity	Structural level an Operation acts on: LEAF, TERM, EQUATION or SYSTEM.
ChangeOfVariables	Rename a coefficient family a(i, ...) -> relation(q(i, ...)) across the model and swap a for q in the unknowns. The unknown swap (model.redeclare_unknown) is what distinguishes it from a plain substitution.

Functions

granularity_of

Return the Granularity of an operation from its system_level / whole_model_op / single_term_only flags.

API

class zoomy_core.model.derivation.operations.SolveFor(variable, name=None)

Bases: zoomy_core.model.operations.Operation

Reorient an equation in place into variable = solution. Pipeline counterpart of equation.solve_for(var), which returns a new equation.

Initialization

Store the variable to isolate.

apply_to_equation(eq)

Replace the equation by the oriented relation variable = solution.

class zoomy_core.model.derivation.operations.SolveLinearSystem(equations, variables, name='solve_linear_system')

Solve a coupled linear system A v = b for a family of variables with sympy.linsolve. solve() returns an indexable MomentFamily of oriented rows v_i = solution_i that can be passed to .apply.

Initialization

Store the equations and the unknown variables.

solve()

Solve the system, hiding opaque Galerkin brackets behind symbols during the solve.

Returns

MomentFamily whose component i is variables[i] = solution_i.

class zoomy_core.model.derivation.operations.Granularity

Structural level an Operation acts on: LEAF, TERM, EQUATION or SYSTEM.

LEAF

‘LEAF’

TERM

‘TERM’

EQUATION

‘EQUATION’

SYSTEM

‘SYSTEM’

zoomy_core.model.derivation.operations.granularity_of(op) → str

Return the Granularity of an operation from its system_level / whole_model_op / single_term_only flags.

Args

• op: an Operation instance.

class zoomy_core.model.derivation.operations.ChangeOfVariables(old, new, relation, name=None)

Bases: zoomy_core.model.operations.Operation

Rename a coefficient family a(i, ...) -> relation(q(i, ...)) across the model and swap a for q in the unknowns. The unknown swap (model.redeclare_unknown) is what distinguishes it from a plain substitution.

Args

• old: name of the family currently in Q.

• new: name of the replacing family.

• relation: callable mapping the applied new function to the substituted expression.

Initialization

Store the family names and the relation.

whole_model_op

True

transforms_bcs

True

apply_to_model(model)

Rewrite every equation and relation, then redeclare the unknowns old -> new.