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The SciMLStructure Interface

Core Interface Definitions

isscimlstructure Definition

isscimlstructure(p)::Bool
ismutablescimlstructure(p)::Bool

Returns whether the object satisfies the SciMLStructure interface. Defaults to false and types are required to opt-into the interface.

canonicalize Definition

canonicalize(::AbstractPortion, p::T1) -> values::T2, repack, aliases::Bool
repack(new_values::T2) -> p::T1 # with values replaced with new_values
replace(::AbstractPortion, p::T1, new_values) -> p::T1
replace!(::AbstractPortion, p::T1, new_values)::Nothing # Requires mutable

Portion Definitions

The core function of the interface is the canonicalize function. canonicalize allows the user to define to the solver how to represent the given "portion" in a standard AbstractVector type which allows for interfacing with standard tools like linear algebra in an efficient manner. The type of portions which are defined are:

  • Tunable: the tunable values/parameters, i.e. the values of the structure which are supposed to be considered non-constant when used in the context of an inverse problem solve. For example, this is the set of parameters to be optimized during a parameter estimation of an ODE.

    • Tunable parameters are expected to return an AbstractVector of unitless values.
    • Tunable parameters are expected to be constant during the solution of the ODE.

  • Constants: the values which are to be considered constant by the solver, i.e. values which are not estimated in an inverse problem and which are unchanged in any operation by the user as part of the solver's usage.

  • Caches: the stored cache values of the struct, i.e. the values of the structure which are used as intermediates within other computations in order to avoid extra allocations.

  • Discrete: the discrete portions of the state captured inside of the structure. For example, discrete values stored outside of the u in the parameters to be modified in the callbacks of an ODE.

    • Any parameter that is modified inside of callbacks should be considered Discrete.

Definitions for Base Objects

  • Vector: returns an aliased version of itself as Tunable, and an empty vector matching type for Constants, Caches, and Discrete.
  • Array: returns the vec(p) aliased version of itself as Tunable, and an empty vector matching type for Constants, Caches, and Discrete.