dolfinx::fem::Expression< T > Class Template Reference

Represents a mathematical expression evaluated at a pre-defined set of points on the reference cell. This class closely follows the concept of a UFC Expression. More...

#include <Expression.h>

Public Types
using	scalar_type = T
	Scalar type (T).

Public Member Functions
	Expression (const std::vector< std::shared_ptr< const fem::Function< T >>> &coefficients, const std::vector< std::shared_ptr< const fem::Constant< T >>> &constants, const std::shared_ptr< const mesh::Mesh > &mesh, const array2d< double > &X, const std::function< void(T *, const T *, const T *, const double *)> fn, const std::size_t value_size)
	Create Expression. More...
	Expression (Expression &&form)=default
	Move constructor.
virtual	~Expression ()=default
	Destructor.
const std::vector< std::shared_ptr< const fem::Function< T > > > &	coefficients () const
	Access coefficients.
std::vector< int >	coefficient_offsets () const
	Offset for each coefficient expansion array on a cell. Used to pack data for multiple coefficients in a flat array. The last entry is the size required to store all coefficients.
void	eval (const xtl::span< const std::int32_t > &active_cells, array2d< T > &values) const
	Evaluate the expression on cells. More...
const std::function< void(T *, const T *, const T *, const double *)> &	get_tabulate_expression () const
	Get function for tabulate_expression. More...
const std::vector< std::shared_ptr< const fem::Constant< T > > > &	constants () const
	Access constants. More...
std::shared_ptr< const mesh::Mesh >	mesh () const
	Get mesh. More...
const array2d< double > &	x () const
	Get evaluation points on reference cell. More...
const std::size_t	value_size () const
	Get value size. More...
const std::size_t	num_points () const
	Get number of points. More...

Detailed Description

template<typename T>
class dolfinx::fem::Expression< T >

Represents a mathematical expression evaluated at a pre-defined set of points on the reference cell. This class closely follows the concept of a UFC Expression.

This functionality can be used to evaluate a gradient of a Function at quadrature points in all cells. This evaluated gradient can then be used as input in to a non-FEniCS function that calculates a material constitutive model.

Constructor & Destructor Documentation

Expression()

template<typename T >

dolfinx::fem::Expression< T >::Expression ( const std::vector< std::shared_ptr< const fem::Function< T >>> &  coefficients, const std::vector< std::shared_ptr< const fem::Constant< T >>> &  constants, const std::shared_ptr< const mesh::Mesh > &  mesh, const array2d< double > &  X, const std::function< void(T *, const T *, const T *, const double *)>  fn, const std::size_t  value_size  )

inline

Create Expression.

Parameters

[in]	coefficients	Coefficients in the Expression
[in]	constants	Constants in the Expression
[in]	mesh
[in]	X	points on reference cell, number of points rows and tdim cols
[in]	fn	function for tabulating expression
[in]	value_size	size of expression evaluated at single point

Member Function Documentation

constants()

template<typename T >

const std::vector<std::shared_ptr<const fem::Constant<T> > >& dolfinx::fem::Expression< T >::constants ( ) const

inline

Access constants.

Returns

Vector of attached constants with their names. Names are used to set constants in user's c++ code. Index in the vector is the position of the constant in the original (nonsimplified) form.

eval()

template<typename T >

void dolfinx::fem::Expression< T >::eval ( const xtl::span< const std::int32_t > &  active_cells, array2d< T > &  values  ) const

inline

Evaluate the expression on cells.

Parameters

[in]	active_cells	Cells on which to evaluate the Expression
[out]	values	To store the result. Caller responsible for correct sizing which should be num_cells rows by num_points*value_size columns.

get_tabulate_expression()

template<typename T >

const std::function<void(T*, const T*, const T*, const double*)>& dolfinx::fem::Expression< T >::get_tabulate_expression ( ) const

inline

Get function for tabulate_expression.

Parameters

[out]

fn

Function to tabulate expression.

mesh()

template<typename T >

std::shared_ptr<const mesh::Mesh> dolfinx::fem::Expression< T >::mesh ( ) const

inline

Get mesh.

Returns

The mesh

num_points()

template<typename T >

const std::size_t dolfinx::fem::Expression< T >::num_points ( ) const

inline

Get number of points.

Returns

number of points

value_size()

template<typename T >

const std::size_t dolfinx::fem::Expression< T >::value_size ( ) const

inline

Get value size.

Returns

value_size

x()

template<typename T >

const array2d<double>& dolfinx::fem::Expression< T >::x ( ) const

inline

Get evaluation points on reference cell.

Returns

Evaluation points

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

• /__w/dolfinx/dolfinx/cpp/dolfinx/fem/evaluate.h
• /__w/dolfinx/dolfinx/cpp/dolfinx/fem/Expression.h