# File invertable_operator.hxx¶

namespace bout

SNB model

namespace inversion

Functions

template<typename T>
T identity(const T &in)

No-op function to use as a default may wish to remove once testing phase complete.

template<typename T>
PetscErrorCode fieldToPetscVec(const T &in, Vec out)

Pack a PetscVec from a Field<T>

template<typename T>
PetscErrorCode petscVecToField(Vec in, T &out)

Pack a Field<T> from a PetscVec.

template<typename T>
class InvertableOperator
#include <invertable_operator.hxx>

Class to define an invertable operator. Provides interface to PETSc routines for solving A.x = b

Public Types

template<>
using data_type = T

What type of field does the operator take?

template<>
using function_signature = std::function<T(const T&)>

The signature of the functor that applies the operator.

Public Functions

InvertableOperator(const function_signature &func = identity<T>, Options *optIn = nullptr, Mesh *localmeshIn = nullptr)

Almost empty constructor currently don’t actually use Options for anything.

~InvertableOperator()

Destructor just has to cleanup the PETSc owned objects.

void setOperatorFunction(const function_signature &func, bool alsoSetPreconditioner = true)

Allow the user to override the existing function Note by default we set the preconditioner function to match this as this is the usual mode of operation. If the user doesn’t want to do this they can set alsoSetPreconditioner to false.

void setPreconditionerFunction(const function_signature &func)

Allow the user to override the existing preconditioner function.

T operator()(const T &input)

Provide a way to apply the operator to a Field.

T apply(const T &input)

Provide a synonym for applying the operator to a Field.

PetscErrorCode setup()

Sets up the PETSc objects required for inverting the operator Currently also takes the functor that applies the operator this class represents. Not actually required by any of the setup so this should probably be moved to a separate place (maybe the constructor).

T invert(const T &rhsField, const T &guess)
T invert(const T &rhsField)

Triggers the solve of A.x = b for x, where b = rhs and A is the matrix representation of the operator we represent. Should probably provide an overload or similar as a way of setting the initial guess.

bool verify(const T &rhsIn, BoutReal tol = 1.0e-5)

With checks enabled provides a convience routine to check that applying the registered function on the calculated inverse gives back the initial values.

Public Static Functions

static void reportTime()

Reports the time spent in various parts of InvertableOperator. Note that as the Timer “labels” are not unique to an instance the time reported is summed across all different instances.

Private Members

Mat matOperator
Mat matPreconditioner
Vec rhs
Vec lhs
KSP ksp
function_signature operatorFunction = identity<T>

The function that represents the operator that we wish to invert.

function_signature preconditionerFunction = identity<T>

The function that represents the preconditioner for the operator that we wish to invert

Options *opt = nullptr
Mesh *localmesh = nullptr
bool doneSetup = false
PetscLib lib

Private Static Functions

static PetscErrorCode functionWrapper(Mat m, Vec v1, Vec v2)

Wrapper that gets a pointer to the parent InvertableOperator instance from the Matrix m and uses this to get the actual function to call. Copies data from v1 into a field of type T, calls the function on this and then copies the result into the v2 argument.

static PetscErrorCode preconditionerWrapper(Mat m, Vec v1, Vec v2)

Wrapper that gets a pointer to the parent InvertableOperator instance from the Matrix m and uses this to get the actual function to call. Copies data from v1 into a field of type T, calls the function on this and then copies the result into the v2 argument.