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Add MappedFiniteElement trait #109

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mscroggs merged 3 commits into from
Nov 25, 2025
Merged

Add MappedFiniteElement trait #109

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c5a21e2
add MappedFiniteElement trait
mscroggs Nov 24, 2025
fe9ace1
doc
mscroggs Nov 24, 2025
c37517f
Merge branch 'main' into mscroggs/mapped-finite-element
mscroggs Nov 24, 2025
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14 changes: 7 additions & 7 deletions src/bindings.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -254,7 +254,7 @@ pub mod ciarlet {
ciarlet::CiarletElement,
map::{ContravariantPiolaMap, CovariantPiolaMap, IdentityMap},
reference_cell,
traits::{ElementFamily, FiniteElement, Map},
traits::{ElementFamily, FiniteElement, Map, MappedFiniteElement},
types::{Continuity, ReferenceCellType},
};
use c_api_tools::{DType, DTypeIdentifier, cfuncs, concretise_types};
Expand Down Expand Up @@ -495,7 +495,7 @@ pub mod ciarlet {
gen_type(name = "maptype", replace_with = ["IdentityMap", "CovariantPiolaMap", "ContravariantPiolaMap"]),
field(arg = 0, name = "element", wrapper = "CiarletElementT", replace_with = ["CiarletElement<{{dtype}}, {{maptype}}>"])
)]
pub fn ciarlet_element_physical_value_size<E: FiniteElement>(
pub fn ciarlet_element_physical_value_size<E: MappedFiniteElement>(
element: &E,
gdim: usize,
) -> usize {
Expand All @@ -507,7 +507,7 @@ pub mod ciarlet {
gen_type(name = "maptype", replace_with = ["IdentityMap", "CovariantPiolaMap", "ContravariantPiolaMap"]),
field(arg = 0, name = "element", wrapper = "CiarletElementT", replace_with = ["CiarletElement<{{dtype}}, {{maptype}}>"])
)]
pub fn ciarlet_element_physical_value_rank<E: FiniteElement>(
pub fn ciarlet_element_physical_value_rank<E: MappedFiniteElement>(
element: &E,
gdim: usize,
) -> usize {
Expand All @@ -519,7 +519,7 @@ pub mod ciarlet {
gen_type(name = "maptype", replace_with = ["IdentityMap", "CovariantPiolaMap", "ContravariantPiolaMap"]),
field(arg = 0, name = "element", wrapper = "CiarletElementT", replace_with = ["CiarletElement<{{dtype}}, {{maptype}}>"])
)]
pub fn ciarlet_element_physical_value_shape<E: FiniteElement>(
pub fn ciarlet_element_physical_value_shape<E: MappedFiniteElement>(
element: &E,
gdim: usize,
shape: *mut usize,
Expand All @@ -537,7 +537,7 @@ pub mod ciarlet {
gen_type(name = "maptype", replace_with = ["IdentityMap", "CovariantPiolaMap", "ContravariantPiolaMap"]),
field(arg = 0, name = "element", wrapper = "CiarletElementT", replace_with = ["CiarletElement<{{dtype}}, {{maptype}}>"])
)]
pub fn ciarlet_element_push_forward<E: FiniteElement<CellType = ReferenceCellType>>(
pub fn ciarlet_element_push_forward<E: MappedFiniteElement<CellType = ReferenceCellType>>(
element: &E,
npoints: usize,
nfunctions: usize,
Expand Down Expand Up @@ -606,7 +606,7 @@ pub mod ciarlet {
gen_type(name = "maptype", replace_with = ["IdentityMap", "CovariantPiolaMap", "ContravariantPiolaMap"]),
field(arg = 0, name = "element", wrapper = "CiarletElementT", replace_with = ["CiarletElement<{{dtype}}, {{maptype}}>"])
)]
pub fn ciarlet_element_pull_back<E: FiniteElement<CellType = ReferenceCellType>>(
pub fn ciarlet_element_pull_back<E: MappedFiniteElement<CellType = ReferenceCellType>>(
element: &E,
npoints: usize,
nfunctions: usize,
Expand Down Expand Up @@ -685,7 +685,7 @@ pub mod ciarlet {
gen_type(name = "maptype", replace_with = ["IdentityMap", "CovariantPiolaMap", "ContravariantPiolaMap"]),
field(arg = 0, name = "element", wrapper = "CiarletElementT", replace_with = ["CiarletElement<{{dtype}}, {{maptype}}>"])
)]
pub fn ciarlet_element_embedded_superdegree<E: FiniteElement>(element: &E) -> usize {
pub fn ciarlet_element_embedded_superdegree<E: MappedFiniteElement>(element: &E) -> usize {
element.lagrange_superdegree()
}

Expand Down
38 changes: 27 additions & 11 deletions src/ciarlet.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,7 @@ extern crate lapack_src;
use crate::math;
use crate::polynomials::{legendre_shape, polynomial_count, tabulate_legendre_polynomials};
use crate::reference_cell;
use crate::traits::{FiniteElement, Map};
use crate::traits::{FiniteElement, Map, MappedFiniteElement};
use crate::types::{Continuity, DofTransformation, ReferenceCellType, Transformation};
use itertools::izip;
use num::{One, Zero};
Expand Down Expand Up @@ -621,26 +621,27 @@ where
&self.interpolation_weights
}
}

impl<T: RlstScalar, M: Map> FiniteElement for CiarletElement<T, M> {
type CellType = ReferenceCellType;
type TransformationType = Transformation;
type T = T;

fn value_shape(&self) -> &[usize] {
&self.value_shape
}

fn value_size(&self) -> usize {
self.value_size
}

fn cell_type(&self) -> ReferenceCellType {
self.cell_type
}
fn lagrange_superdegree(&self) -> usize {
self.embedded_superdegree
}

fn dim(&self) -> usize {
self.dim
}

fn tabulate<
Array2Impl: ValueArrayImpl<<Self::T as RlstScalar>::Real, 2>,
Array4MutImpl: MutableArrayImpl<Self::T, 4>,
Expand Down Expand Up @@ -681,27 +682,39 @@ impl<T: RlstScalar, M: Map> FiniteElement for CiarletElement<T, M> {
}
}
}

fn tabulate_array_shape(&self, nderivs: usize, npoints: usize) -> [usize; 4] {
let deriv_count = compute_derivative_count(nderivs, self.cell_type());
let point_count = npoints;
let basis_count = self.dim();
let value_size = self.value_size();
[deriv_count, point_count, basis_count, value_size]
}

fn entity_dofs(&self, entity_dim: usize, entity_number: usize) -> Option<&[usize]> {
if entity_dim < 4 && entity_number < self.entity_dofs[entity_dim].len() {
Some(&self.entity_dofs[entity_dim][entity_number])
} else {
None
}
}

fn entity_closure_dofs(&self, entity_dim: usize, entity_number: usize) -> Option<&[usize]> {
if entity_dim < 4 && entity_number < self.entity_closure_dofs[entity_dim].len() {
Some(&self.entity_closure_dofs[entity_dim][entity_number])
} else {
None
}
}
fn tabulate_array_shape(&self, nderivs: usize, npoints: usize) -> [usize; 4] {
let deriv_count = compute_derivative_count(nderivs, self.cell_type());
let point_count = npoints;
let basis_count = self.dim();
let value_size = self.value_size();
[deriv_count, point_count, basis_count, value_size]
}

impl<T: RlstScalar, M: Map> MappedFiniteElement for CiarletElement<T, M> {
type TransformationType = Transformation;

fn lagrange_superdegree(&self) -> usize {
self.embedded_superdegree
}

fn push_forward<
Array3RealImpl: ValueArrayImpl<<Self::T as RlstScalar>::Real, 3>,
Array4Impl: ValueArrayImpl<Self::T, 4>,
Expand All @@ -724,6 +737,7 @@ impl<T: RlstScalar, M: Map> FiniteElement for CiarletElement<T, M> {
physical_values,
)
}

fn pull_back<
Array3RealImpl: ValueArrayImpl<<Self::T as RlstScalar>::Real, 3>,
Array4Impl: ValueArrayImpl<Self::T, 4>,
Expand All @@ -746,9 +760,11 @@ impl<T: RlstScalar, M: Map> FiniteElement for CiarletElement<T, M> {
reference_values,
)
}

fn physical_value_shape(&self, gdim: usize) -> Vec<usize> {
self.map.physical_value_shape(gdim)
}

fn dof_transformation(
&self,
entity: ReferenceCellType,
Expand Down
37 changes: 20 additions & 17 deletions src/traits.rs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@ use rlst::{Array, MutableArrayImpl, RlstScalar, ValueArrayImpl};
use std::fmt::Debug;
use std::hash::Hash;

/// This trait provides the definition of a finite element.
/// A finite element.
pub trait FiniteElement {
/// The scalar type
type T: RlstScalar;
Expand All @@ -14,21 +14,9 @@ pub trait FiniteElement {
/// The cell type is typically defined through [ReferenceCellType](crate::types::ReferenceCellType).
type CellType: Debug + PartialEq + Eq + Clone + Copy + Hash;

/// Transformation type
///
/// The Transformation type specifies possible transformations of the dofs on the reference element.
/// In most cases these will be rotations and reflections as defined in [Transformation](crate::types::Transformation).
type TransformationType: Debug + PartialEq + Eq + Clone + Copy + Hash;

/// The reference cell type, eg one of `Point`, `Interval`, `Triangle`, etc.
fn cell_type(&self) -> Self::CellType;

/// The smallest degree Lagrange space that contains all possible polynomials of the finite element's polynomial space.
///
/// Details on the definition of the degree of Lagrange spaces of finite elements are
/// given [here](https://defelement.org/ciarlet.html#The+degree+of+a+finite+element).
fn lagrange_superdegree(&self) -> usize;

/// The number of basis functions.
fn dim(&self) -> usize;

Expand Down Expand Up @@ -75,6 +63,9 @@ pub trait FiniteElement {
data: &mut Array<Array4MutImpl, 4>,
);

/// Get the required shape for a tabulation array.
fn tabulate_array_shape(&self, nderivs: usize, npoints: usize) -> [usize; 4];

/// Return the dof indices that are associated with the subentity with index `entity_number` and dimension `entity_dim`.
///
/// - For `entity_dim = 0` this returns the degrees of freedom (dofs) associated with the corresponding point.
Expand All @@ -92,9 +83,21 @@ pub trait FiniteElement {
/// associated with the boundary of an entity. For an edge (for example) it returns the dofs associated
/// with the vertices at the boundary of the edge (as well as the dofs associated with the edge itself).
fn entity_closure_dofs(&self, entity_dim: usize, entity_number: usize) -> Option<&[usize]>;
}

/// Get the required shape for a tabulation array.
fn tabulate_array_shape(&self, nderivs: usize, npoints: usize) -> [usize; 4];
/// A finite element that is mapped from a reference cell.
pub trait MappedFiniteElement: FiniteElement {
/// Transformation type
///
/// The Transformation type specifies possible transformations of the dofs on the reference element.
/// In most cases these will be rotations and reflections as defined in [Transformation](crate::types::Transformation).
type TransformationType: Debug + PartialEq + Eq + Clone + Copy + Hash;

/// The smallest degree Lagrange space that contains all possible polynomials of the finite element's polynomial space.
///
/// Details on the definition of the degree of Lagrange spaces of finite elements are
/// given [here](https://defelement.org/ciarlet.html#The+degree+of+a+finite+element).
fn lagrange_superdegree(&self) -> usize;

/// Push function values forward to a physical cell.
///
Expand All @@ -117,7 +120,7 @@ pub trait FiniteElement {
/// is the topological dimension, and the third dimension is the geometric dimension. If the Jacobian is rectangular then the
/// inverse Jacobian is the pseudo-inverse of the Jacobian, ie the matrix $J^\dagger$ such that $J^\dagger J = I$.
/// - `physical_values`: The output array of the push operation. This shape of this array is the same as the `reference_values`
/// input, with the [FiniteElement::physical_value_size] used instead of the reference value size.
/// input, with the [MappedFiniteElement::physical_value_size] used instead of the reference value size.
fn push_forward<
Array3RealImpl: ValueArrayImpl<<Self::T as RlstScalar>::Real, 3>,
Array4Impl: ValueArrayImpl<Self::T, 4>,
Expand All @@ -134,7 +137,7 @@ pub trait FiniteElement {

/// Pull function values back to the reference cell.
///
/// This is the inverse operation to [FiniteElement::push_forward].
/// This is the inverse operation to [MappedFiniteElement::push_forward].
fn pull_back<
Array3RealImpl: ValueArrayImpl<<Self::T as RlstScalar>::Real, 3>,
Array4Impl: ValueArrayImpl<Self::T, 4>,
Expand Down