Note: this is documentation for an old release. View the latest documentation at docs.fenicsproject.org/basix/v0.8.0/cpp/namespacebasix_1_1moments.html

# Basix 0.7.0

## HomeInstallationDemosC++ docsPython docs

basix::moments Namespace Reference

Functions to create integral moment DOFs. More...

## Functions

template<std::floating_point T>
std::tuple< std::vector< std::vector< T > >, std::array< std::size_t, 2 >, std::vector< std::vector< T > >, std::array< std::size_t, 4 > > make_integral_moments (const FiniteElement< T > &moment_space, cell::type celltype, polyset::type ptype, std::size_t value_size, int q_deg)
Make interpolation points and weights for simple integral moments. More...

template<std::floating_point T>
std::tuple< std::vector< std::vector< T > >, std::array< std::size_t, 2 >, std::vector< std::vector< T > >, std::array< std::size_t, 4 > > make_dot_integral_moments (const FiniteElement< T > &V, cell::type celltype, polyset::type ptype, std::size_t value_size, int q_deg)
Make interpolation points and weights for dot product integral moments. More...

template<std::floating_point T>
std::tuple< std::vector< std::vector< T > >, std::array< std::size_t, 2 >, std::vector< std::vector< T > >, std::array< std::size_t, 4 > > make_tangent_integral_moments (const FiniteElement< T > &V, cell::type celltype, polyset::type ptype, std::size_t value_size, int q_deg)
Make interpolation points and weights for tangent integral moments. More...

template<std::floating_point T>
std::tuple< std::vector< std::vector< T > >, std::array< std::size_t, 2 >, std::vector< std::vector< T > >, std::array< std::size_t, 4 > > make_normal_integral_moments (const FiniteElement< T > &V, cell::type celltype, polyset::type ptype, std::size_t value_size, int q_deg)
Compute interpolation points and weights for normal integral moments. More...

## Detailed Description

Functions to create integral moment DOFs.

## ◆ make_dot_integral_moments()

template<std::floating_point T>
 std::tuple< std::vector< std::vector< T > >, std::array< std::size_t, 2 >, std::vector< std::vector< T > >, std::array< std::size_t, 4 > > basix::moments::make_dot_integral_moments ( const FiniteElement< T > & V, cell::type celltype, polyset::type ptype, std::size_t value_size, int q_deg )

Make interpolation points and weights for dot product integral moments.

These will represent the integral of each function in the moment space over each sub entity of the moment space's cell type in a cell with the given type. For example, if the input cell type is a triangle and the moment space is a P1 space on an edge, this will perform two integrals for each of the 3 edges of the triangle.

Todo:
Clarify what happens value size of the moment space is less than value_size.
Parameters
 V The space to compute the integral moments against celltype The cell type of the cell on which the space is being defined ptype The polyset type of the element this moment is being used to define value_size The value size of the space being defined q_deg The quadrature degree used for the integrals
Returns
(interpolation points, interpolation shape, interpolation matrix, interpolation shape). The indices of the interpolation points are (number of entities, npoints, gdim). The indices on the interpolation matrix are (number of entities, ndofs, value_size, npoints, derivative)

## ◆ make_integral_moments()

template<std::floating_point T>
 std::tuple< std::vector< std::vector< T > >, std::array< std::size_t, 2 >, std::vector< std::vector< T > >, std::array< std::size_t, 4 > > basix::moments::make_integral_moments ( const FiniteElement< T > & moment_space, cell::type celltype, polyset::type ptype, std::size_t value_size, int q_deg )

Make interpolation points and weights for simple integral moments.

These will represent the integral of each function in the moment space over each sub entity of the moment space's cell type in a cell with the given type. For example, if the input cell type is a triangle, and the moment space is a P1 space on an edge, this will perform two integrals for each of the 3 edges of the triangle.

Parameters
 moment_space The space to compute the integral moments against celltype The cell type of the cell on which the space is being defined ptype The polyset type of the element this moment is being used to define value_size The value size of the space being defined q_deg The quadrature degree used for the integrals
Returns
(interpolation points, interpolation matrix). The indices of the interpolation points are (number of entities, npoints, gdim). The indices on the interpolation matrix are (number of entities, ndofs, value_size, npoints, derivative)

## ◆ make_normal_integral_moments()

template<std::floating_point T>
 std::tuple< std::vector< std::vector< T > >, std::array< std::size_t, 2 >, std::vector< std::vector< T > >, std::array< std::size_t, 4 > > basix::moments::make_normal_integral_moments ( const FiniteElement< T > & V, cell::type celltype, polyset::type ptype, std::size_t value_size, int q_deg )

Compute interpolation points and weights for normal integral moments.

These can only be used when the moment space is defined on facets of the cell.

Parameters
 [in] V The space to compute the integral moments against [in] celltype The cell type of the cell on which the space is being defined ptype The polyset type of the element this moment is being used to define [in] value_size The value size of the space being defined [in] q_deg The quadrature degree used for the integrals
Returns
(interpolation points, interpolation shape, interpolation matrix, interpolation shape). The indices of the interpolation points are (number of entities, npoints, gdim). The indices on the interpolation matrix are (number of entities, ndofs, value_size, npoints, derivative)

## ◆ make_tangent_integral_moments()

template<std::floating_point T>
 std::tuple< std::vector< std::vector< T > >, std::array< std::size_t, 2 >, std::vector< std::vector< T > >, std::array< std::size_t, 4 > > basix::moments::make_tangent_integral_moments ( const FiniteElement< T > & V, cell::type celltype, polyset::type ptype, std::size_t value_size, int q_deg )

Make interpolation points and weights for tangent integral moments.

These can only be used when the moment space is defined on edges of the cell.

Parameters
 V The space to compute the integral moments against celltype The cell type of the cell on which the space is being defined ptype The polyset type of the element this moment is being used to define value_size The value size of the space being defined the space q_deg The quadrature degree used for the integrals
Returns
(interpolation points, interpolation shape, interpolation matrix, interpolation shape). The indices of the interpolation points are (number of entities, npoints, gdim). The indices on the interpolation matrix are (number of entities, ndofs, value_size, npoints, derivative)