Function

class dolfin.cpp.function.Function(*args)

Bases: dolfin.cpp.function.GenericFunction, dolfin.cpp.function.HierarchicalFunction

This class represents a function \(u_h\) in a finite element function space \(V_h\) , given by .. math:

::

u_h = sum_{i=1}^{n} U_i phi_i

where \(\phi_i\}_{i=1}^{n}\) is a basis for \(V_h\) , and \(U\) is a vector of expansion coefficients for \(u_h\) .

Friends: FunctionAssigner, FunctionSpace.

Sub-function constructor with shallow copy of vector (used in Python interface) Arguments v (Function ) The function to be copied. i (std::size_t) Index of subfunction.

Parameters:

• Function & v (const) –
• i (std::size_t) –

child()

Return the child Function in the hierarchy

compute_vertex_values()

Compute values at all mesh vertices

Parameters:

• double > & vertex_values (std::vector<) – (Array<double>) The values at all vertices.
• Mesh & mesh (const) – (Mesh ) The mesh.

Return type:

void

copy(deepcopy=False)

Return a copy of itself

Arguments

deepcopy (bool)

If false (default) the dof vector is shared.

Returns

_Function_

The Function

eval()

Evaluate function at given coordinates

Parameters:

• double > & values (Array<) – (Array<double>) The values.
• Array< double > & x (const) – (Array<double>) The coordinates.

Return type:

void

extrapolate()

Extrapolate function (from a possibly lower-degree function space) Arguments v (Function ) The function to be extrapolated.

Parameters:Function & v (const) – Return type:void

function_space()

Return the FunctionSpace

geometric_dimension()

Return geometric dimension Returns std::size_t The geometric dimension.

Return type:std::size_t

get_allow_extrapolation()

Check if extrapolation is permitted when evaluating the Function

Return type:bool Returns:bool True if extrapolation is permitted, otherwise false

interpolate()

Interpolate function (on possibly non-matching meshes)

Parameters:GenericFunction & v (const) – (GenericFunction ) The function to be interpolated. Return type:void

leaf_node()

Return the finest Function in hierarchy

parent()

Return the parent Function in the hierarchy

root_node()

Return the coarsest Function in hierarchy

set_allow_extrapolation()

Allow extrapolation when evaluating the Function

Parameters:allow_extrapolation (bool) – (bool) Whether or not permit extrapolation. Return type:void

sub()

Extract subfunction Arguments i (std::size_t) Index of subfunction. Returns:cpp:any:Function The subfunction.

Parameters:i (std::size_t) – Return type:Function &

thisown

The membership flag

vector()

Return vector of expansion coefficients (non-const version) Returns:cpp:any:GenericVector The vector of expansion coefficients.

Return type:std::shared_ptr< GenericVector >