Reference documentation for deal.II version GIT relicensing-1308-g50a4ffc717 2024-07-25 10:40:01+00:00
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Public Types | Public Member Functions | Static Public Member Functions | Private Types | Private Member Functions | Private Attributes | Static Private Attributes | List of all members
FESeries::Legendre< dim, spacedim > Class Template Reference

#include <deal.II/fe/fe_series.h>

Inheritance diagram for FESeries::Legendre< dim, spacedim >:
Inheritance graph

Public Types

using CoefficientType = double

Public Member Functions

 Legendre (const std::vector< unsigned int > &n_coefficients_per_direction, const hp::FECollection< dim, spacedim > &fe_collection, const hp::QCollection< dim > &q_collection, const unsigned int component=numbers::invalid_unsigned_int)
template<typename Number >
void calculate (const ::Vector< Number > &local_dof_values, const unsigned int cell_active_fe_index, Table< dim, CoefficientType > &legendre_coefficients)
unsigned int get_n_coefficients_per_direction (const unsigned int index) const
void precalculate_all_transformation_matrices ()
template<class Archive >
void save_transformation_matrices (Archive &ar, const unsigned int version)
template<class Archive >
void load_transformation_matrices (Archive &ar, const unsigned int version)
bool operator== (const Legendre< dim, spacedim > &legendre) const
template<class Archive >
void serialize (Archive &ar, const unsigned int version)
Subscriptor functionality

Classes derived from Subscriptor provide a facility to subscribe to this object. This is mostly used by the SmartPointer class.

void subscribe (std::atomic< bool > *const validity, const std::string &identifier="") const
void unsubscribe (std::atomic< bool > *const validity, const std::string &identifier="") const
unsigned int n_subscriptions () const
template<typename StreamType >
void list_subscribers (StreamType &stream) const
void list_subscribers () const

Static Public Member Functions

static ::ExceptionBaseExcInUse (int arg1, std::string arg2, std::string arg3)
static ::ExceptionBaseExcNoSubscriber (std::string arg1, std::string arg2)

Private Types

using map_value_type = decltype(counter_map)::value_type
using map_iterator = decltype(counter_map)::iterator

Private Member Functions

void check_no_subscribers () const noexcept

Private Attributes

const std::vector< unsigned intn_coefficients_per_direction
SmartPointer< const hp::FECollection< dim, spacedim > > fe_collection
const hp::QCollection< dim > q_collection
std::vector< FullMatrix< CoefficientType > > legendre_transform_matrices
std::vector< CoefficientTypeunrolled_coefficients
const unsigned int component
std::atomic< unsigned intcounter
std::map< std::string, unsigned intcounter_map
std::vector< std::atomic< bool > * > validity_pointers
const std::type_info * object_info

Static Private Attributes

static std::mutex mutex

Detailed Description

template<int dim, int spacedim = dim>
class FESeries::Legendre< dim, spacedim >

A class to calculate expansion of a scalar FE (or a single component of vector-valued FE) field into series of Legendre functions on a reference element.

Legendre functions are solutions to Legendre's differential equation

\[ \frac{d}{dx}\left([1-x^2] \frac{d}{dx} P_n(x)\right) + n[n+1] P_n(x) = 0 \]

and can be expressed using Rodrigues' formula

\[ P_n(x) = \frac{1}{2^n n!} \frac{d^n}{dx^n}[x^2-1]^n. \]

These polynomials are orthogonal with respect to the \( L^2 \) inner product on the interval \( [-1;1] \)

\[ \int_{-1}^1 P_m(x) P_n(x) = \frac{2}{2n + 1} \delta_{mn} \]

and are complete. A family of \( L^2 \)-orthogonal polynomials on \( [0;1] \) can be constructed via

\[ \widetilde P_m = \sqrt{2} P_m(2x-1). \]

An arbitrary scalar FE field on the reference element \( [0;1] \) can be expanded in the complete orthogonal basis as

\[ u(x) = \sum_{m} c_m \widetilde P_{m}(x). \]

From the orthogonality property of the basis, it follows that

\[ c_m = \frac{2m+1}{2} \int_0^1 u(x) \widetilde P_m(x) dx . \]

This class calculates coefficients \( c_{\bf k} \) using \( dim \)-dimensional Legendre polynomials constructed from \( \widetilde P_m(x) \) using tensor product rule.

Definition at line 259 of file fe_series.h.

Member Typedef Documentation

◆ CoefficientType

template<int dim, int spacedim = dim>
using FESeries::Legendre< dim, spacedim >::CoefficientType = double

Definition at line 262 of file fe_series.h.

◆ map_value_type

using Subscriptor::map_value_type = decltype(counter_map)::value_type

The data type used in counter_map.

Definition at line 229 of file subscriptor.h.

◆ map_iterator

using Subscriptor::map_iterator = decltype(counter_map)::iterator

The iterator type used in counter_map.

Definition at line 234 of file subscriptor.h.

Constructor & Destructor Documentation

◆ Legendre()

template<int dim, int spacedim>
FESeries::Legendre< dim, spacedim >::Legendre ( const std::vector< unsigned int > &  n_coefficients_per_direction,
const hp::FECollection< dim, spacedim > &  fe_collection,
const hp::QCollection< dim > &  q_collection,
const unsigned int  component = numbers::invalid_unsigned_int 

Constructor that initializes all required data structures.

The n_coefficients_per_direction defines the number of coefficients in each direction, fe_collection is the hp::FECollection for which expansion will be used and q_collection is the hp::QCollection used to integrate the expansion for each FiniteElement in fe_collection.

As the Legendre expansion can only be performed on scalar fields, this class does not operate on vector-valued finite elements and will therefore throw an assertion. However, each component of a finite element field can be treated as a scalar field, respectively, on which Legendre expansions are again possible. For this purpose, the optional parameter component defines which component of each FiniteElement will be used. The default value of component only applies to scalar FEs, in which case it indicates that the sole component is to be decomposed. For vector-valued FEs, a non-default value must be explicitly provided.

Definition at line 198 of file

Member Function Documentation

◆ calculate()

template<int dim, int spacedim>
template<typename Number >
void FESeries::Legendre< dim, spacedim >::calculate ( const ::Vector< Number > &  local_dof_values,
const unsigned int  cell_active_fe_index,
Table< dim, CoefficientType > &  legendre_coefficients 

Calculate legendre_coefficients of the cell vector field given by local_dof_values corresponding to FiniteElement with cell_active_fe_index .

Definition at line 281 of file

◆ get_n_coefficients_per_direction()

template<int dim, int spacedim>
unsigned int FESeries::Legendre< dim, spacedim >::get_n_coefficients_per_direction ( const unsigned int  index) const

Return the number of coefficients in each coordinate direction for the finite element associated with index in the provided hp::FECollection.

Definition at line 270 of file

◆ precalculate_all_transformation_matrices()

template<int dim, int spacedim>
void FESeries::Legendre< dim, spacedim >::precalculate_all_transformation_matrices ( )

Calculate all transformation matrices to transfer the finite element solution to the series expansion representation.

These matrices will be generated on demand by calling calculate() and stored for recurring purposes. Usually, this operation consumes a lot of workload. With this function, all matrices will be calculated in advance. This way, we can separate their costly generation from the actual application.

Definition at line 250 of file

◆ save_transformation_matrices()

template<int dim, int spacedim = dim>
template<class Archive >
void FESeries::Legendre< dim, spacedim >::save_transformation_matrices ( Archive &  ar,
const unsigned int  version 

Write all transformation matrices of this object to a stream for the purpose of serialization.

Since any of its transformation matrices has to be generated only once for a given scenario, it is common practice to determine them in advance calling precalculate_all_transformation_matrices() and keep them via serialization.

◆ load_transformation_matrices()

template<int dim, int spacedim = dim>
template<class Archive >
void FESeries::Legendre< dim, spacedim >::load_transformation_matrices ( Archive &  ar,
const unsigned int  version 

Read all transformation matrices from a stream and recover them for this object.

◆ operator==()

template<int dim, int spacedim>
bool FESeries::Legendre< dim, spacedim >::operator== ( const Legendre< dim, spacedim > &  legendre) const

Test for equality of two series expansion objects.

Definition at line 235 of file

◆ subscribe()

void Subscriptor::subscribe ( std::atomic< bool > *const  validity,
const std::string &  identifier = "" 
) const

Subscribes a user of the object by storing the pointer validity. The subscriber may be identified by text supplied as identifier.

Definition at line 135 of file

◆ unsubscribe()

void Subscriptor::unsubscribe ( std::atomic< bool > *const  validity,
const std::string &  identifier = "" 
) const

Unsubscribes a user from the object.

The identifier and the validity pointer must be the same as the one supplied to subscribe().

Definition at line 155 of file

◆ n_subscriptions()

unsigned int Subscriptor::n_subscriptions ( ) const

Return the present number of subscriptions to this object. This allows to use this class for reference counted lifetime determination where the last one to unsubscribe also deletes the object.

Definition at line 300 of file subscriptor.h.

◆ list_subscribers() [1/2]

template<typename StreamType >
void Subscriptor::list_subscribers ( StreamType &  stream) const

List the subscribers to the input stream.

Definition at line 317 of file subscriptor.h.

◆ list_subscribers() [2/2]

void Subscriptor::list_subscribers ( ) const

List the subscribers to deallog.

Definition at line 203 of file

◆ serialize()

template<class Archive >
void Subscriptor::serialize ( Archive &  ar,
const unsigned int  version 

Read or write the data of this object to or from a stream for the purpose of serialization using the BOOST serialization library.

This function does not actually serialize any of the member variables of this class. The reason is that what this class stores is only who subscribes to this object, but who does so at the time of storing the contents of this object does not necessarily have anything to do with who subscribes to the object when it is restored. Consequently, we do not want to overwrite the subscribers at the time of restoring, and then there is no reason to write the subscribers out in the first place.

Definition at line 309 of file subscriptor.h.

◆ check_no_subscribers()

void Subscriptor::check_no_subscribers ( ) const

Check that there are no objects subscribing to this object. If this check passes then it is safe to destroy the current object. It this check fails then this function will either abort or print an error message to deallog (by using the AssertNothrow mechanism), but will not throw an exception.

Since this function is just a consistency check it does nothing in release mode.
If this function is called when there is an uncaught exception then, rather than aborting, this function prints an error message to the standard error stream and returns.

Definition at line 52 of file

Member Data Documentation

◆ n_coefficients_per_direction

template<int dim, int spacedim = dim>
const std::vector<unsigned int> FESeries::Legendre< dim, spacedim >::n_coefficients_per_direction

Number of coefficients in each direction for each finite element in the registered hp::FECollection.

Definition at line 350 of file fe_series.h.

◆ fe_collection

template<int dim, int spacedim = dim>
SmartPointer<const hp::FECollection<dim, spacedim> > FESeries::Legendre< dim, spacedim >::fe_collection

hp::FECollection for which transformation matrices will be calculated.

Definition at line 355 of file fe_series.h.

◆ q_collection

template<int dim, int spacedim = dim>
const hp::QCollection<dim> FESeries::Legendre< dim, spacedim >::q_collection

hp::QCollection used in calculation of transformation matrices.

Definition at line 360 of file fe_series.h.

◆ legendre_transform_matrices

template<int dim, int spacedim = dim>
std::vector<FullMatrix<CoefficientType> > FESeries::Legendre< dim, spacedim >::legendre_transform_matrices

Transformation matrices for each FiniteElement.

Definition at line 365 of file fe_series.h.

◆ unrolled_coefficients

template<int dim, int spacedim = dim>
std::vector<CoefficientType> FESeries::Legendre< dim, spacedim >::unrolled_coefficients

Auxiliary vector to store unrolled coefficients.

Definition at line 370 of file fe_series.h.

◆ component

template<int dim, int spacedim = dim>
const unsigned int FESeries::Legendre< dim, spacedim >::component

Which component of FiniteElement should be used to calculate the expansion.

Definition at line 376 of file fe_series.h.

◆ counter

std::atomic<unsigned int> Subscriptor::counter

Store the number of objects which subscribed to this object. Initially, this number is zero, and upon destruction it shall be zero again (i.e. all objects which subscribed should have unsubscribed again).

The creator (and owner) of an object is counted in the map below if HE manages to supply identification.

We use the mutable keyword in order to allow subscription to constant objects also.

This counter may be read from and written to concurrently in multithreaded code: hence we use the std::atomic class template.

Definition at line 218 of file subscriptor.h.

◆ counter_map

std::map<std::string, unsigned int> Subscriptor::counter_map

In this map, we count subscriptions for each different identification string supplied to subscribe().

Definition at line 224 of file subscriptor.h.

◆ validity_pointers

std::vector<std::atomic<bool> *> Subscriptor::validity_pointers

In this vector, we store pointers to the validity bool in the SmartPointer objects that subscribe to this class.

Definition at line 240 of file subscriptor.h.

◆ object_info

const std::type_info* Subscriptor::object_info

Pointer to the typeinfo object of this object, from which we can later deduce the class name. Since this information on the derived class is neither available in the destructor, nor in the constructor, we obtain it in between and store it here.

Definition at line 248 of file subscriptor.h.

◆ mutex

std::mutex Subscriptor::mutex

A mutex used to ensure data consistency when accessing the mutable members of this class. This lock is used in the subscribe() and unsubscribe() functions, as well as in list_subscribers().

Definition at line 271 of file subscriptor.h.

The documentation for this class was generated from the following files: